linux/fs/ext4/sysfs.c

698 lines
19 KiB

License cleanup: add SPDX GPL-2.0 license identifier to files with no license Many source files in the tree are missing licensing information, which makes it harder for compliance tools to determine the correct license. By default all files without license information are under the default license of the kernel, which is GPL version 2. Update the files which contain no license information with the 'GPL-2.0' SPDX license identifier. The SPDX identifier is a legally binding shorthand, which can be used instead of the full boiler plate text. This patch is based on work done by Thomas Gleixner and Kate Stewart and Philippe Ombredanne. How this work was done: Patches were generated and checked against linux-4.14-rc6 for a subset of the use cases: - file had no licensing information it it. - file was a */uapi/* one with no licensing information in it, - file was a */uapi/* one with existing licensing information, Further patches will be generated in subsequent months to fix up cases where non-standard license headers were used, and references to license had to be inferred by heuristics based on keywords. The analysis to determine which SPDX License Identifier to be applied to a file was done in a spreadsheet of side by side results from of the output of two independent scanners (ScanCode & Windriver) producing SPDX tag:value files created by Philippe Ombredanne. Philippe prepared the base worksheet, and did an initial spot review of a few 1000 files. The 4.13 kernel was the starting point of the analysis with 60,537 files assessed. Kate Stewart did a file by file comparison of the scanner results in the spreadsheet to determine which SPDX license identifier(s) to be applied to the file. She confirmed any determination that was not immediately clear with lawyers working with the Linux Foundation. Criteria used to select files for SPDX license identifier tagging was: - Files considered eligible had to be source code files. - Make and config files were included as candidates if they contained >5 lines of source - File already had some variant of a license header in it (even if <5 lines). All documentation files were explicitly excluded. The following heuristics were used to determine which SPDX license identifiers to apply. - when both scanners couldn't find any license traces, file was considered to have no license information in it, and the top level COPYING file license applied. For non */uapi/* files that summary was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 11139 and resulted in the first patch in this series. If that file was a */uapi/* path one, it was "GPL-2.0 WITH Linux-syscall-note" otherwise it was "GPL-2.0". Results of that was: SPDX license identifier # files ---------------------------------------------------|------- GPL-2.0 WITH Linux-syscall-note 930 and resulted in the second patch in this series. - if a file had some form of licensing information in it, and was one of the */uapi/* ones, it was denoted with the Linux-syscall-note if any GPL family license was found in the file or had no licensing in it (per prior point). Results summary: SPDX license identifier # files ---------------------------------------------------|------ GPL-2.0 WITH Linux-syscall-note 270 GPL-2.0+ WITH Linux-syscall-note 169 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-2-Clause) 21 ((GPL-2.0 WITH Linux-syscall-note) OR BSD-3-Clause) 17 LGPL-2.1+ WITH Linux-syscall-note 15 GPL-1.0+ WITH Linux-syscall-note 14 ((GPL-2.0+ WITH Linux-syscall-note) OR BSD-3-Clause) 5 LGPL-2.0+ WITH Linux-syscall-note 4 LGPL-2.1 WITH Linux-syscall-note 3 ((GPL-2.0 WITH Linux-syscall-note) OR MIT) 3 ((GPL-2.0 WITH Linux-syscall-note) AND MIT) 1 and that resulted in the third patch in this series. - when the two scanners agreed on the detected license(s), that became the concluded license(s). - when there was disagreement between the two scanners (one detected a license but the other didn't, or they both detected different licenses) a manual inspection of the file occurred. - In most cases a manual inspection of the information in the file resulted in a clear resolution of the license that should apply (and which scanner probably needed to revisit its heuristics). - When it was not immediately clear, the license identifier was confirmed with lawyers working with the Linux Foundation. - If there was any question as to the appropriate license identifier, the file was flagged for further research and to be revisited later in time. In total, over 70 hours of logged manual review was done on the spreadsheet to determine the SPDX license identifiers to apply to the source files by Kate, Philippe, Thomas and, in some cases, confirmation by lawyers working with the Linux Foundation. Kate also obtained a third independent scan of the 4.13 code base from FOSSology, and compared selected files where the other two scanners disagreed against that SPDX file, to see if there was new insights. The Windriver scanner is based on an older version of FOSSology in part, so they are related. Thomas did random spot checks in about 500 files from the spreadsheets for the uapi headers and agreed with SPDX license identifier in the files he inspected. For the non-uapi files Thomas did random spot checks in about 15000 files. In initial set of patches against 4.14-rc6, 3 files were found to have copy/paste license identifier errors, and have been fixed to reflect the correct identifier. Additionally Philippe spent 10 hours this week doing a detailed manual inspection and review of the 12,461 patched files from the initial patch version early this week with: - a full scancode scan run, collecting the matched texts, detected license ids and scores - reviewing anything where there was a license detected (about 500+ files) to ensure that the applied SPDX license was correct - reviewing anything where there was no detection but the patch license was not GPL-2.0 WITH Linux-syscall-note to ensure that the applied SPDX license was correct This produced a worksheet with 20 files needing minor correction. This worksheet was then exported into 3 different .csv files for the different types of files to be modified. These .csv files were then reviewed by Greg. Thomas wrote a script to parse the csv files and add the proper SPDX tag to the file, in the format that the file expected. This script was further refined by Greg based on the output to detect more types of files automatically and to distinguish between header and source .c files (which need different comment types.) Finally Greg ran the script using the .csv files to generate the patches. Reviewed-by: Kate Stewart <kstewart@linuxfoundation.org> Reviewed-by: Philippe Ombredanne <pombredanne@nexb.com> Reviewed-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-01 15:07:57 +01:00
ext4: shrink race window in ext4_should_retry_alloc() When generic/371 is run on kvm-xfstests using 5.10 and 5.11 kernels, it fails at significant rates on the two test scenarios that disable delayed allocation (ext3conv and data_journal) and force actual block allocation for the fallocate and pwrite functions in the test. The failure rate on 5.10 for both ext3conv and data_journal on one test system typically runs about 85%. On 5.11, the failure rate on ext3conv sometimes drops to as low as 1% while the rate on data_journal increases to nearly 100%. The observed failures are largely due to ext4_should_retry_alloc() cutting off block allocation retries when s_mb_free_pending (used to indicate that a transaction in progress will free blocks) is 0. However, free space is usually available when this occurs during runs of generic/371. It appears that a thread attempting to allocate blocks is just missing transaction commits in other threads that increase the free cluster count and reset s_mb_free_pending while the allocating thread isn't running. Explicitly testing for free space availability avoids this race. The current code uses a post-increment operator in the conditional expression that determines whether the retry limit has been exceeded. This means that the conditional expression uses the value of the retry counter before it's increased, resulting in an extra retry cycle. The current code actually retries twice before hitting its retry limit rather than once. Increasing the retry limit to 3 from the current actual maximum retry count of 2 in combination with the change described above reduces the observed failure rate to less that 0.1% on both ext3conv and data_journal with what should be limited impact on users sensitive to the overhead caused by retries. A per filesystem percpu counter exported via sysfs is added to allow users or developers to track the number of times the retry limit is exceeded without resorting to debugging methods. This should provide some insight into worst case retry behavior. Signed-off-by: Eric Whitney <enwlinux@gmail.com> Link: https://lore.kernel.org/r/20210218151132.19678-1-enwlinux@gmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2021-02-18 10:11:32 -05:00
ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists() We can trigger a slab-out-of-bounds with the following commands: mkfs.ext4 -F /dev/$disk 10G mount /dev/$disk /tmp/test echo 2147483647 > /sys/fs/ext4/$disk/mb_group_prealloc echo test > /tmp/test/file && sync ================================================================== BUG: KASAN: slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] Read of size 8 at addr ffff888121b9d0f0 by task kworker/u2:0/11 CPU: 0 PID: 11 Comm: kworker/u2:0 Tainted: GL 6.7.0-next-20240118 #521 Call Trace: dump_stack_lvl+0x2c/0x50 kasan_report+0xb6/0xf0 ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] ext4_mb_regular_allocator+0x19e9/0x2370 [ext4] ext4_mb_new_blocks+0x88a/0x1370 [ext4] ext4_ext_map_blocks+0x14f7/0x2390 [ext4] ext4_map_blocks+0x569/0xea0 [ext4] ext4_do_writepages+0x10f6/0x1bc0 [ext4] [...] ================================================================== The flow of issue triggering is as follows: // Set s_mb_group_prealloc to 2147483647 via sysfs ext4_mb_new_blocks ext4_mb_normalize_request ext4_mb_normalize_group_request ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc ext4_mb_regular_allocator ext4_mb_choose_next_group ext4_mb_choose_next_group_best_avail mb_avg_fragment_size_order order = fls(len) - 2 = 29 ext4_mb_find_good_group_avg_frag_lists frag_list = &sbi->s_mb_avg_fragment_size[order] if (list_empty(frag_list)) // Trigger SOOB! At 4k block size, the length of the s_mb_avg_fragment_size list is 14, but an oversized s_mb_group_prealloc is set, causing slab-out-of-bounds to be triggered by an attempt to access an element at index 29. Add a new attr_id attr_clusters_in_group with values in the range [0, sbi->s_clusters_per_group] and declare mb_group_prealloc as that type to fix the issue. In addition avoid returning an order from mb_avg_fragment_size_order() greater than MB_NUM_ORDERS(sb) and reduce some useless loops. Fixes: 7e170922f06b ("ext4: Add allocation criteria 1.5 (CR1_5)") CC: stable@vger.kernel.org Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Link: https://lore.kernel.org/r/20240319113325.3110393-5-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2024-03-19 19:33:20 +08:00
ext4: shrink race window in ext4_should_retry_alloc() When generic/371 is run on kvm-xfstests using 5.10 and 5.11 kernels, it fails at significant rates on the two test scenarios that disable delayed allocation (ext3conv and data_journal) and force actual block allocation for the fallocate and pwrite functions in the test. The failure rate on 5.10 for both ext3conv and data_journal on one test system typically runs about 85%. On 5.11, the failure rate on ext3conv sometimes drops to as low as 1% while the rate on data_journal increases to nearly 100%. The observed failures are largely due to ext4_should_retry_alloc() cutting off block allocation retries when s_mb_free_pending (used to indicate that a transaction in progress will free blocks) is 0. However, free space is usually available when this occurs during runs of generic/371. It appears that a thread attempting to allocate blocks is just missing transaction commits in other threads that increase the free cluster count and reset s_mb_free_pending while the allocating thread isn't running. Explicitly testing for free space availability avoids this race. The current code uses a post-increment operator in the conditional expression that determines whether the retry limit has been exceeded. This means that the conditional expression uses the value of the retry counter before it's increased, resulting in an extra retry cycle. The current code actually retries twice before hitting its retry limit rather than once. Increasing the retry limit to 3 from the current actual maximum retry count of 2 in combination with the change described above reduces the observed failure rate to less that 0.1% on both ext3conv and data_journal with what should be limited impact on users sensitive to the overhead caused by retries. A per filesystem percpu counter exported via sysfs is added to allow users or developers to track the number of times the retry limit is exceeded without resorting to debugging methods. This should provide some insight into worst case retry behavior. Signed-off-by: Eric Whitney <enwlinux@gmail.com> Link: https://lore.kernel.org/r/20210218151132.19678-1-enwlinux@gmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2021-02-18 10:11:32 -05:00
ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists() We can trigger a slab-out-of-bounds with the following commands: mkfs.ext4 -F /dev/$disk 10G mount /dev/$disk /tmp/test echo 2147483647 > /sys/fs/ext4/$disk/mb_group_prealloc echo test > /tmp/test/file && sync ================================================================== BUG: KASAN: slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] Read of size 8 at addr ffff888121b9d0f0 by task kworker/u2:0/11 CPU: 0 PID: 11 Comm: kworker/u2:0 Tainted: GL 6.7.0-next-20240118 #521 Call Trace: dump_stack_lvl+0x2c/0x50 kasan_report+0xb6/0xf0 ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] ext4_mb_regular_allocator+0x19e9/0x2370 [ext4] ext4_mb_new_blocks+0x88a/0x1370 [ext4] ext4_ext_map_blocks+0x14f7/0x2390 [ext4] ext4_map_blocks+0x569/0xea0 [ext4] ext4_do_writepages+0x10f6/0x1bc0 [ext4] [...] ================================================================== The flow of issue triggering is as follows: // Set s_mb_group_prealloc to 2147483647 via sysfs ext4_mb_new_blocks ext4_mb_normalize_request ext4_mb_normalize_group_request ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc ext4_mb_regular_allocator ext4_mb_choose_next_group ext4_mb_choose_next_group_best_avail mb_avg_fragment_size_order order = fls(len) - 2 = 29 ext4_mb_find_good_group_avg_frag_lists frag_list = &sbi->s_mb_avg_fragment_size[order] if (list_empty(frag_list)) // Trigger SOOB! At 4k block size, the length of the s_mb_avg_fragment_size list is 14, but an oversized s_mb_group_prealloc is set, causing slab-out-of-bounds to be triggered by an attempt to access an element at index 29. Add a new attr_id attr_clusters_in_group with values in the range [0, sbi->s_clusters_per_group] and declare mb_group_prealloc as that type to fix the issue. In addition avoid returning an order from mb_avg_fragment_size_order() greater than MB_NUM_ORDERS(sb) and reduce some useless loops. Fixes: 7e170922f06b ("ext4: Add allocation criteria 1.5 (CR1_5)") CC: stable@vger.kernel.org Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Link: https://lore.kernel.org/r/20240319113325.3110393-5-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2024-03-19 19:33:20 +08:00
ext4: improve cr 0 / cr 1 group scanning Instead of traversing through groups linearly, scan groups in specific orders at cr 0 and cr 1. At cr 0, we want to find groups that have the largest free order >= the order of the request. So, with this patch, we maintain lists for each possible order and insert each group into a list based on the largest free order in its buddy bitmap. During cr 0 allocation, we traverse these lists in the increasing order of largest free orders. This allows us to find a group with the best available cr 0 match in constant time. If nothing can be found, we fallback to cr 1 immediately. At CR1, the story is slightly different. We want to traverse in the order of increasing average fragment size. For CR1, we maintain a rb tree of groupinfos which is sorted by average fragment size. Instead of traversing linearly, at CR1, we traverse in the order of increasing average fragment size, starting at the most optimal group. This brings down cr 1 search complexity to log(num groups). For cr >= 2, we just perform the linear search as before. Also, in case of lock contention, we intermittently fallback to linear search even in CR 0 and CR 1 cases. This allows us to proceed during the allocation path even in case of high contention. There is an opportunity to do optimization at CR2 too. That's because at CR2 we only consider groups where bb_free counter (number of free blocks) is greater than the request extent size. That's left as future work. All the changes introduced in this patch are protected under a new mount option "mb_optimize_scan". With this patchset, following experiment was performed: Created a highly fragmented disk of size 65TB. The disk had no contiguous 2M regions. Following command was run consecutively for 3 times: time dd if=/dev/urandom of=file bs=2M count=10 Here are the results with and without cr 0/1 optimizations introduced in this patch: |---------+------------------------------+---------------------------| | | Without CR 0/1 Optimizations | With CR 0/1 Optimizations | |---------+------------------------------+---------------------------| | 1st run | 5m1.871s | 2m47.642s | | 2nd run | 2m28.390s | 0m0.611s | | 3rd run | 2m26.530s | 0m1.255s | |---------+------------------------------+---------------------------| Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com> Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Andreas Dilger <adilger@dilger.ca> Link: https://lore.kernel.org/r/20210401172129.189766-6-harshadshirwadkar@gmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2021-04-01 10:21:27 -07:00
ext4: shrink race window in ext4_should_retry_alloc() When generic/371 is run on kvm-xfstests using 5.10 and 5.11 kernels, it fails at significant rates on the two test scenarios that disable delayed allocation (ext3conv and data_journal) and force actual block allocation for the fallocate and pwrite functions in the test. The failure rate on 5.10 for both ext3conv and data_journal on one test system typically runs about 85%. On 5.11, the failure rate on ext3conv sometimes drops to as low as 1% while the rate on data_journal increases to nearly 100%. The observed failures are largely due to ext4_should_retry_alloc() cutting off block allocation retries when s_mb_free_pending (used to indicate that a transaction in progress will free blocks) is 0. However, free space is usually available when this occurs during runs of generic/371. It appears that a thread attempting to allocate blocks is just missing transaction commits in other threads that increase the free cluster count and reset s_mb_free_pending while the allocating thread isn't running. Explicitly testing for free space availability avoids this race. The current code uses a post-increment operator in the conditional expression that determines whether the retry limit has been exceeded. This means that the conditional expression uses the value of the retry counter before it's increased, resulting in an extra retry cycle. The current code actually retries twice before hitting its retry limit rather than once. Increasing the retry limit to 3 from the current actual maximum retry count of 2 in combination with the change described above reduces the observed failure rate to less that 0.1% on both ext3conv and data_journal with what should be limited impact on users sensitive to the overhead caused by retries. A per filesystem percpu counter exported via sysfs is added to allow users or developers to track the number of times the retry limit is exceeded without resorting to debugging methods. This should provide some insight into worst case retry behavior. Signed-off-by: Eric Whitney <enwlinux@gmail.com> Link: https://lore.kernel.org/r/20210218151132.19678-1-enwlinux@gmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2021-02-18 10:11:32 -05:00
ext4: improve cr 0 / cr 1 group scanning Instead of traversing through groups linearly, scan groups in specific orders at cr 0 and cr 1. At cr 0, we want to find groups that have the largest free order >= the order of the request. So, with this patch, we maintain lists for each possible order and insert each group into a list based on the largest free order in its buddy bitmap. During cr 0 allocation, we traverse these lists in the increasing order of largest free orders. This allows us to find a group with the best available cr 0 match in constant time. If nothing can be found, we fallback to cr 1 immediately. At CR1, the story is slightly different. We want to traverse in the order of increasing average fragment size. For CR1, we maintain a rb tree of groupinfos which is sorted by average fragment size. Instead of traversing linearly, at CR1, we traverse in the order of increasing average fragment size, starting at the most optimal group. This brings down cr 1 search complexity to log(num groups). For cr >= 2, we just perform the linear search as before. Also, in case of lock contention, we intermittently fallback to linear search even in CR 0 and CR 1 cases. This allows us to proceed during the allocation path even in case of high contention. There is an opportunity to do optimization at CR2 too. That's because at CR2 we only consider groups where bb_free counter (number of free blocks) is greater than the request extent size. That's left as future work. All the changes introduced in this patch are protected under a new mount option "mb_optimize_scan". With this patchset, following experiment was performed: Created a highly fragmented disk of size 65TB. The disk had no contiguous 2M regions. Following command was run consecutively for 3 times: time dd if=/dev/urandom of=file bs=2M count=10 Here are the results with and without cr 0/1 optimizations introduced in this patch: |---------+------------------------------+---------------------------| | | Without CR 0/1 Optimizations | With CR 0/1 Optimizations | |---------+------------------------------+---------------------------| | 1st run | 5m1.871s | 2m47.642s | | 2nd run | 2m28.390s | 0m0.611s | | 3rd run | 2m26.530s | 0m1.255s | |---------+------------------------------+---------------------------| Signed-off-by: Harshad Shirwadkar <harshadshirwadkar@gmail.com> Reported-by: kernel test robot <lkp@intel.com> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by: Andreas Dilger <adilger@dilger.ca> Link: https://lore.kernel.org/r/20210401172129.189766-6-harshadshirwadkar@gmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2021-04-01 10:21:27 -07:00
fscrypt: support test_dummy_encryption=v2 v1 encryption policies are deprecated in favor of v2, and some new features (e.g. encryption+casefolding) are only being added for v2. Therefore, the "test_dummy_encryption" mount option (which is used for encryption I/O testing with xfstests) needs to support v2 policies. To do this, extend its syntax to be "test_dummy_encryption=v1" or "test_dummy_encryption=v2". The existing "test_dummy_encryption" (no argument) also continues to be accepted, to specify the default setting -- currently v1, but the next patch changes it to v2. To cleanly support both v1 and v2 while also making it easy to support specifying other encryption settings in the future (say, accepting "$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a pointer to the dummy fscrypt_context rather than using mount flags. To avoid concurrency issues, don't allow test_dummy_encryption to be set or changed during a remount. (The former restriction is new, but xfstests doesn't run into it, so no one should notice.) Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'. On ext4, there are two regressions, both of which are test bugs: ext4/023 and ext4/028 fail because they set an xattr and expect it to be stored inline, but the increase in size of the fscrypt_context from 24 to 40 bytes causes this xattr to be spilled into an external block. Link: https://lore.kernel.org/r/20200512233251.118314-4-ebiggers@kernel.org Acked-by: Jaegeuk Kim <jaegeuk@kernel.org> Reviewed-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Eric Biggers <ebiggers@google.com>
2020-05-12 16:32:50 -07:00
ext4: add basic fs-verity support Add most of fs-verity support to ext4. fs-verity is a filesystem feature that enables transparent integrity protection and authentication of read-only files. It uses a dm-verity like mechanism at the file level: a Merkle tree is used to verify any block in the file in log(filesize) time. It is implemented mainly by helper functions in fs/verity/. See Documentation/filesystems/fsverity.rst for the full documentation. This commit adds all of ext4 fs-verity support except for the actual data verification, including: - Adding a filesystem feature flag and an inode flag for fs-verity. - Implementing the fsverity_operations to support enabling verity on an inode and reading/writing the verity metadata. - Updating ->write_begin(), ->write_end(), and ->writepages() to support writing verity metadata pages. - Calling the fs-verity hooks for ->open(), ->setattr(), and ->ioctl(). ext4 stores the verity metadata (Merkle tree and fsverity_descriptor) past the end of the file, starting at the first 64K boundary beyond i_size. This approach works because (a) verity files are readonly, and (b) pages fully beyond i_size aren't visible to userspace but can be read/written internally by ext4 with only some relatively small changes to ext4. This approach avoids having to depend on the EA_INODE feature and on rearchitecturing ext4's xattr support to support paging multi-gigabyte xattrs into memory, and to support encrypting xattrs. Note that the verity metadata *must* be encrypted when the file is, since it contains hashes of the plaintext data. This patch incorporates work by Theodore Ts'o and Chandan Rajendra. Reviewed-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Eric Biggers <ebiggers@google.com>
2019-07-22 09:26:24 -07:00
ext4: enable block size larger than page size Since block device (See commit 3c20917120ce ("block/bdev: enable large folio support for large logical block sizes")) and page cache (See commit ab95d23bab220ef8 ("filemap: allocate mapping_min_order folios in the page cache")) has the ability to have a minimum order when allocating folio, and ext4 has supported large folio in commit 7ac67301e82f ("ext4: enable large folio for regular file"), now add support for block_size > PAGE_SIZE in ext4. set_blocksize() -> bdev_validate_blocksize() already validates the block size, so ext4_load_super() does not need to perform additional checks. Here we only need to add the FS_LBS bit to fs_flags. In addition, block sizes larger than the page size are currently supported only when CONFIG_TRANSPARENT_HUGEPAGE is enabled. To make this explicit, a blocksize_gt_pagesize entry has been added under /sys/fs/ext4/feature/, indicating whether bs > ps is supported. This allows mke2fs to check the interface and determine whether a warning should be issued when formatting a filesystem with block size larger than the page size. Suggested-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Pankaj Raghav <p.raghav@samsung.com> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Message-ID: <20251121090654.631996-25-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2025-11-21 17:06:54 +08:00
fscrypt: support test_dummy_encryption=v2 v1 encryption policies are deprecated in favor of v2, and some new features (e.g. encryption+casefolding) are only being added for v2. Therefore, the "test_dummy_encryption" mount option (which is used for encryption I/O testing with xfstests) needs to support v2 policies. To do this, extend its syntax to be "test_dummy_encryption=v1" or "test_dummy_encryption=v2". The existing "test_dummy_encryption" (no argument) also continues to be accepted, to specify the default setting -- currently v1, but the next patch changes it to v2. To cleanly support both v1 and v2 while also making it easy to support specifying other encryption settings in the future (say, accepting "$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a pointer to the dummy fscrypt_context rather than using mount flags. To avoid concurrency issues, don't allow test_dummy_encryption to be set or changed during a remount. (The former restriction is new, but xfstests doesn't run into it, so no one should notice.) Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'. On ext4, there are two regressions, both of which are test bugs: ext4/023 and ext4/028 fail because they set an xattr and expect it to be stored inline, but the increase in size of the fscrypt_context from 24 to 40 bytes causes this xattr to be spilled into an external block. Link: https://lore.kernel.org/r/20200512233251.118314-4-ebiggers@kernel.org Acked-by: Jaegeuk Kim <jaegeuk@kernel.org> Reviewed-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Eric Biggers <ebiggers@google.com>
2020-05-12 16:32:50 -07:00
ext4: add basic fs-verity support Add most of fs-verity support to ext4. fs-verity is a filesystem feature that enables transparent integrity protection and authentication of read-only files. It uses a dm-verity like mechanism at the file level: a Merkle tree is used to verify any block in the file in log(filesize) time. It is implemented mainly by helper functions in fs/verity/. See Documentation/filesystems/fsverity.rst for the full documentation. This commit adds all of ext4 fs-verity support except for the actual data verification, including: - Adding a filesystem feature flag and an inode flag for fs-verity. - Implementing the fsverity_operations to support enabling verity on an inode and reading/writing the verity metadata. - Updating ->write_begin(), ->write_end(), and ->writepages() to support writing verity metadata pages. - Calling the fs-verity hooks for ->open(), ->setattr(), and ->ioctl(). ext4 stores the verity metadata (Merkle tree and fsverity_descriptor) past the end of the file, starting at the first 64K boundary beyond i_size. This approach works because (a) verity files are readonly, and (b) pages fully beyond i_size aren't visible to userspace but can be read/written internally by ext4 with only some relatively small changes to ext4. This approach avoids having to depend on the EA_INODE feature and on rearchitecturing ext4's xattr support to support paging multi-gigabyte xattrs into memory, and to support encrypting xattrs. Note that the verity metadata *must* be encrypted when the file is, since it contains hashes of the plaintext data. This patch incorporates work by Theodore Ts'o and Chandan Rajendra. Reviewed-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Eric Biggers <ebiggers@google.com>
2019-07-22 09:26:24 -07:00
ext4: enable block size larger than page size Since block device (See commit 3c20917120ce ("block/bdev: enable large folio support for large logical block sizes")) and page cache (See commit ab95d23bab220ef8 ("filemap: allocate mapping_min_order folios in the page cache")) has the ability to have a minimum order when allocating folio, and ext4 has supported large folio in commit 7ac67301e82f ("ext4: enable large folio for regular file"), now add support for block_size > PAGE_SIZE in ext4. set_blocksize() -> bdev_validate_blocksize() already validates the block size, so ext4_load_super() does not need to perform additional checks. Here we only need to add the FS_LBS bit to fs_flags. In addition, block sizes larger than the page size are currently supported only when CONFIG_TRANSPARENT_HUGEPAGE is enabled. To make this explicit, a blocksize_gt_pagesize entry has been added under /sys/fs/ext4/feature/, indicating whether bs > ps is supported. This allows mke2fs to check the interface and determine whether a warning should be issued when formatting a filesystem with block size larger than the page size. Suggested-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Zhang Yi <yi.zhang@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Pankaj Raghav <p.raghav@samsung.com> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Message-ID: <20251121090654.631996-25-libaokun@huaweicloud.com> Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2025-11-21 17:06:54 +08:00
ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists() We can trigger a slab-out-of-bounds with the following commands: mkfs.ext4 -F /dev/$disk 10G mount /dev/$disk /tmp/test echo 2147483647 > /sys/fs/ext4/$disk/mb_group_prealloc echo test > /tmp/test/file && sync ================================================================== BUG: KASAN: slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] Read of size 8 at addr ffff888121b9d0f0 by task kworker/u2:0/11 CPU: 0 PID: 11 Comm: kworker/u2:0 Tainted: GL 6.7.0-next-20240118 #521 Call Trace: dump_stack_lvl+0x2c/0x50 kasan_report+0xb6/0xf0 ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] ext4_mb_regular_allocator+0x19e9/0x2370 [ext4] ext4_mb_new_blocks+0x88a/0x1370 [ext4] ext4_ext_map_blocks+0x14f7/0x2390 [ext4] ext4_map_blocks+0x569/0xea0 [ext4] ext4_do_writepages+0x10f6/0x1bc0 [ext4] [...] ================================================================== The flow of issue triggering is as follows: // Set s_mb_group_prealloc to 2147483647 via sysfs ext4_mb_new_blocks ext4_mb_normalize_request ext4_mb_normalize_group_request ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc ext4_mb_regular_allocator ext4_mb_choose_next_group ext4_mb_choose_next_group_best_avail mb_avg_fragment_size_order order = fls(len) - 2 = 29 ext4_mb_find_good_group_avg_frag_lists frag_list = &sbi->s_mb_avg_fragment_size[order] if (list_empty(frag_list)) // Trigger SOOB! At 4k block size, the length of the s_mb_avg_fragment_size list is 14, but an oversized s_mb_group_prealloc is set, causing slab-out-of-bounds to be triggered by an attempt to access an element at index 29. Add a new attr_id attr_clusters_in_group with values in the range [0, sbi->s_clusters_per_group] and declare mb_group_prealloc as that type to fix the issue. In addition avoid returning an order from mb_avg_fragment_size_order() greater than MB_NUM_ORDERS(sb) and reduce some useless loops. Fixes: 7e170922f06b ("ext4: Add allocation criteria 1.5 (CR1_5)") CC: stable@vger.kernel.org Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Link: https://lore.kernel.org/r/20240319113325.3110393-5-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2024-03-19 19:33:20 +08:00
ext4: shrink race window in ext4_should_retry_alloc() When generic/371 is run on kvm-xfstests using 5.10 and 5.11 kernels, it fails at significant rates on the two test scenarios that disable delayed allocation (ext3conv and data_journal) and force actual block allocation for the fallocate and pwrite functions in the test. The failure rate on 5.10 for both ext3conv and data_journal on one test system typically runs about 85%. On 5.11, the failure rate on ext3conv sometimes drops to as low as 1% while the rate on data_journal increases to nearly 100%. The observed failures are largely due to ext4_should_retry_alloc() cutting off block allocation retries when s_mb_free_pending (used to indicate that a transaction in progress will free blocks) is 0. However, free space is usually available when this occurs during runs of generic/371. It appears that a thread attempting to allocate blocks is just missing transaction commits in other threads that increase the free cluster count and reset s_mb_free_pending while the allocating thread isn't running. Explicitly testing for free space availability avoids this race. The current code uses a post-increment operator in the conditional expression that determines whether the retry limit has been exceeded. This means that the conditional expression uses the value of the retry counter before it's increased, resulting in an extra retry cycle. The current code actually retries twice before hitting its retry limit rather than once. Increasing the retry limit to 3 from the current actual maximum retry count of 2 in combination with the change described above reduces the observed failure rate to less that 0.1% on both ext3conv and data_journal with what should be limited impact on users sensitive to the overhead caused by retries. A per filesystem percpu counter exported via sysfs is added to allow users or developers to track the number of times the retry limit is exceeded without resorting to debugging methods. This should provide some insight into worst case retry behavior. Signed-off-by: Eric Whitney <enwlinux@gmail.com> Link: https://lore.kernel.org/r/20210218151132.19678-1-enwlinux@gmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2021-02-18 10:11:32 -05:00
ext4: shrink race window in ext4_should_retry_alloc() When generic/371 is run on kvm-xfstests using 5.10 and 5.11 kernels, it fails at significant rates on the two test scenarios that disable delayed allocation (ext3conv and data_journal) and force actual block allocation for the fallocate and pwrite functions in the test. The failure rate on 5.10 for both ext3conv and data_journal on one test system typically runs about 85%. On 5.11, the failure rate on ext3conv sometimes drops to as low as 1% while the rate on data_journal increases to nearly 100%. The observed failures are largely due to ext4_should_retry_alloc() cutting off block allocation retries when s_mb_free_pending (used to indicate that a transaction in progress will free blocks) is 0. However, free space is usually available when this occurs during runs of generic/371. It appears that a thread attempting to allocate blocks is just missing transaction commits in other threads that increase the free cluster count and reset s_mb_free_pending while the allocating thread isn't running. Explicitly testing for free space availability avoids this race. The current code uses a post-increment operator in the conditional expression that determines whether the retry limit has been exceeded. This means that the conditional expression uses the value of the retry counter before it's increased, resulting in an extra retry cycle. The current code actually retries twice before hitting its retry limit rather than once. Increasing the retry limit to 3 from the current actual maximum retry count of 2 in combination with the change described above reduces the observed failure rate to less that 0.1% on both ext3conv and data_journal with what should be limited impact on users sensitive to the overhead caused by retries. A per filesystem percpu counter exported via sysfs is added to allow users or developers to track the number of times the retry limit is exceeded without resorting to debugging methods. This should provide some insight into worst case retry behavior. Signed-off-by: Eric Whitney <enwlinux@gmail.com> Link: https://lore.kernel.org/r/20210218151132.19678-1-enwlinux@gmail.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2021-02-18 10:11:32 -05:00
ext4: fix slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists() We can trigger a slab-out-of-bounds with the following commands: mkfs.ext4 -F /dev/$disk 10G mount /dev/$disk /tmp/test echo 2147483647 > /sys/fs/ext4/$disk/mb_group_prealloc echo test > /tmp/test/file && sync ================================================================== BUG: KASAN: slab-out-of-bounds in ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] Read of size 8 at addr ffff888121b9d0f0 by task kworker/u2:0/11 CPU: 0 PID: 11 Comm: kworker/u2:0 Tainted: GL 6.7.0-next-20240118 #521 Call Trace: dump_stack_lvl+0x2c/0x50 kasan_report+0xb6/0xf0 ext4_mb_find_good_group_avg_frag_lists+0x8a/0x200 [ext4] ext4_mb_regular_allocator+0x19e9/0x2370 [ext4] ext4_mb_new_blocks+0x88a/0x1370 [ext4] ext4_ext_map_blocks+0x14f7/0x2390 [ext4] ext4_map_blocks+0x569/0xea0 [ext4] ext4_do_writepages+0x10f6/0x1bc0 [ext4] [...] ================================================================== The flow of issue triggering is as follows: // Set s_mb_group_prealloc to 2147483647 via sysfs ext4_mb_new_blocks ext4_mb_normalize_request ext4_mb_normalize_group_request ac->ac_g_ex.fe_len = EXT4_SB(sb)->s_mb_group_prealloc ext4_mb_regular_allocator ext4_mb_choose_next_group ext4_mb_choose_next_group_best_avail mb_avg_fragment_size_order order = fls(len) - 2 = 29 ext4_mb_find_good_group_avg_frag_lists frag_list = &sbi->s_mb_avg_fragment_size[order] if (list_empty(frag_list)) // Trigger SOOB! At 4k block size, the length of the s_mb_avg_fragment_size list is 14, but an oversized s_mb_group_prealloc is set, causing slab-out-of-bounds to be triggered by an attempt to access an element at index 29. Add a new attr_id attr_clusters_in_group with values in the range [0, sbi->s_clusters_per_group] and declare mb_group_prealloc as that type to fix the issue. In addition avoid returning an order from mb_avg_fragment_size_order() greater than MB_NUM_ORDERS(sb) and reduce some useless loops. Fixes: 7e170922f06b ("ext4: Add allocation criteria 1.5 (CR1_5)") CC: stable@vger.kernel.org Signed-off-by: Baokun Li <libaokun1@huawei.com> Reviewed-by: Jan Kara <jack@suse.cz> Reviewed-by: Ojaswin Mujoo <ojaswin@linux.ibm.com> Link: https://lore.kernel.org/r/20240319113325.3110393-5-libaokun1@huawei.com Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2024-03-19 19:33:20 +08:00
ext4: fix function prototype mismatch for ext4_feat_ktype With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG), indirect call targets are validated against the expected function pointer prototype to make sure the call target is valid to help mitigate ROP attacks. If they are not identical, there is a failure at run time, which manifests as either a kernel panic or thread getting killed. ext4_feat_ktype was setting the "release" handler to "kfree", which doesn't have a matching function prototype. Add a simple wrapper with the correct prototype. This was found as a result of Clang's new -Wcast-function-type-strict flag, which is more sensitive than the simpler -Wcast-function-type, which only checks for type width mismatches. Note that this code is only reached when ext4 is a loadable module and it is being unloaded: CFI failure at kobject_put+0xbb/0x1b0 (target: kfree+0x0/0x180; expected type: 0x7c4aa698) ... RIP: 0010:kobject_put+0xbb/0x1b0 ... Call Trace: <TASK> ext4_exit_sysfs+0x14/0x60 [ext4] cleanup_module+0x67/0xedb [ext4] Fixes: b99fee58a20a ("ext4: create ext4_feat kobject dynamically") Cc: Theodore Ts'o <tytso@mit.edu> Cc: Eric Biggers <ebiggers@kernel.org> Cc: stable@vger.kernel.org Build-tested-by: Gustavo A. R. Silva <gustavoars@kernel.org> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/r/20230103234616.never.915-kees@kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20230104210908.gonna.388-kees@kernel.org Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2023-01-04 13:09:12 -08:00
ext4: fix function prototype mismatch for ext4_feat_ktype With clang's kernel control flow integrity (kCFI, CONFIG_CFI_CLANG), indirect call targets are validated against the expected function pointer prototype to make sure the call target is valid to help mitigate ROP attacks. If they are not identical, there is a failure at run time, which manifests as either a kernel panic or thread getting killed. ext4_feat_ktype was setting the "release" handler to "kfree", which doesn't have a matching function prototype. Add a simple wrapper with the correct prototype. This was found as a result of Clang's new -Wcast-function-type-strict flag, which is more sensitive than the simpler -Wcast-function-type, which only checks for type width mismatches. Note that this code is only reached when ext4 is a loadable module and it is being unloaded: CFI failure at kobject_put+0xbb/0x1b0 (target: kfree+0x0/0x180; expected type: 0x7c4aa698) ... RIP: 0010:kobject_put+0xbb/0x1b0 ... Call Trace: <TASK> ext4_exit_sysfs+0x14/0x60 [ext4] cleanup_module+0x67/0xedb [ext4] Fixes: b99fee58a20a ("ext4: create ext4_feat kobject dynamically") Cc: Theodore Ts'o <tytso@mit.edu> Cc: Eric Biggers <ebiggers@kernel.org> Cc: stable@vger.kernel.org Build-tested-by: Gustavo A. R. Silva <gustavoars@kernel.org> Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org> Reviewed-by: Nathan Chancellor <nathan@kernel.org> Link: https://lore.kernel.org/r/20230103234616.never.915-kees@kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: Eric Biggers <ebiggers@google.com> Link: https://lore.kernel.org/r/20230104210908.gonna.388-kees@kernel.org Signed-off-by: Theodore Ts'o <tytso@mit.edu>
2023-01-04 13:09:12 -08:00
ext4: fix use-after-free in update_super_work when racing with umount Commit b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") moved ext4_unregister_sysfs() before flushing s_sb_upd_work to prevent new error work from being queued via /proc/fs/ext4/xx/mb_groups reads during unmount. However, this introduced a use-after-free because update_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which accesses the kobject's kernfs_node after it has been freed by kobject_del() in ext4_unregister_sysfs(): update_super_work ext4_put_super ----------------- -------------- ext4_unregister_sysfs(sb) kobject_del(&sbi->s_kobj) __kobject_del() sysfs_remove_dir() kobj->sd = NULL sysfs_put(sd) kernfs_put() // RCU free ext4_notify_error_sysfs(sbi) sysfs_notify(&sbi->s_kobj) kn = kobj->sd // stale pointer kernfs_get(kn) // UAF on freed kernfs_node ext4_journal_destroy() flush_work(&sbi->s_sb_upd_work) Instead of reordering the teardown sequence, fix this by making ext4_notify_error_sysfs() detect that sysfs has already been torn down by checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call in that case. A dedicated mutex (s_error_notify_mutex) serializes ext4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs() to prevent TOCTOU races where the kobject could be deleted between the state_in_sysfs check and the sysfs_notify() call. Fixes: b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") Cc: Jiayuan Chen <jiayuan.chen@linux.dev> Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://patch.msgid.link/20260319120336.157873-1-jiayuan.chen@linux.dev Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org
2026-03-19 20:03:35 +08:00
ext4: fix use-after-free in update_super_work when racing with umount Commit b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") moved ext4_unregister_sysfs() before flushing s_sb_upd_work to prevent new error work from being queued via /proc/fs/ext4/xx/mb_groups reads during unmount. However, this introduced a use-after-free because update_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which accesses the kobject's kernfs_node after it has been freed by kobject_del() in ext4_unregister_sysfs(): update_super_work ext4_put_super ----------------- -------------- ext4_unregister_sysfs(sb) kobject_del(&sbi->s_kobj) __kobject_del() sysfs_remove_dir() kobj->sd = NULL sysfs_put(sd) kernfs_put() // RCU free ext4_notify_error_sysfs(sbi) sysfs_notify(&sbi->s_kobj) kn = kobj->sd // stale pointer kernfs_get(kn) // UAF on freed kernfs_node ext4_journal_destroy() flush_work(&sbi->s_sb_upd_work) Instead of reordering the teardown sequence, fix this by making ext4_notify_error_sysfs() detect that sysfs has already been torn down by checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call in that case. A dedicated mutex (s_error_notify_mutex) serializes ext4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs() to prevent TOCTOU races where the kobject could be deleted between the state_in_sysfs check and the sysfs_notify() call. Fixes: b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") Cc: Jiayuan Chen <jiayuan.chen@linux.dev> Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://patch.msgid.link/20260319120336.157873-1-jiayuan.chen@linux.dev Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org
2026-03-19 20:03:35 +08:00
ext4: fix use-after-free in update_super_work when racing with umount Commit b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") moved ext4_unregister_sysfs() before flushing s_sb_upd_work to prevent new error work from being queued via /proc/fs/ext4/xx/mb_groups reads during unmount. However, this introduced a use-after-free because update_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which accesses the kobject's kernfs_node after it has been freed by kobject_del() in ext4_unregister_sysfs(): update_super_work ext4_put_super ----------------- -------------- ext4_unregister_sysfs(sb) kobject_del(&sbi->s_kobj) __kobject_del() sysfs_remove_dir() kobj->sd = NULL sysfs_put(sd) kernfs_put() // RCU free ext4_notify_error_sysfs(sbi) sysfs_notify(&sbi->s_kobj) kn = kobj->sd // stale pointer kernfs_get(kn) // UAF on freed kernfs_node ext4_journal_destroy() flush_work(&sbi->s_sb_upd_work) Instead of reordering the teardown sequence, fix this by making ext4_notify_error_sysfs() detect that sysfs has already been torn down by checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call in that case. A dedicated mutex (s_error_notify_mutex) serializes ext4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs() to prevent TOCTOU races where the kobject could be deleted between the state_in_sysfs check and the sysfs_notify() call. Fixes: b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") Cc: Jiayuan Chen <jiayuan.chen@linux.dev> Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://patch.msgid.link/20260319120336.157873-1-jiayuan.chen@linux.dev Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org
2026-03-19 20:03:35 +08:00
ext4: fix use-after-free in update_super_work when racing with umount Commit b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") moved ext4_unregister_sysfs() before flushing s_sb_upd_work to prevent new error work from being queued via /proc/fs/ext4/xx/mb_groups reads during unmount. However, this introduced a use-after-free because update_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which accesses the kobject's kernfs_node after it has been freed by kobject_del() in ext4_unregister_sysfs(): update_super_work ext4_put_super ----------------- -------------- ext4_unregister_sysfs(sb) kobject_del(&sbi->s_kobj) __kobject_del() sysfs_remove_dir() kobj->sd = NULL sysfs_put(sd) kernfs_put() // RCU free ext4_notify_error_sysfs(sbi) sysfs_notify(&sbi->s_kobj) kn = kobj->sd // stale pointer kernfs_get(kn) // UAF on freed kernfs_node ext4_journal_destroy() flush_work(&sbi->s_sb_upd_work) Instead of reordering the teardown sequence, fix this by making ext4_notify_error_sysfs() detect that sysfs has already been torn down by checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call in that case. A dedicated mutex (s_error_notify_mutex) serializes ext4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs() to prevent TOCTOU races where the kobject could be deleted between the state_in_sysfs check and the sysfs_notify() call. Fixes: b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") Cc: Jiayuan Chen <jiayuan.chen@linux.dev> Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://patch.msgid.link/20260319120336.157873-1-jiayuan.chen@linux.dev Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org
2026-03-19 20:03:35 +08:00
ext4: fix use-after-free in update_super_work when racing with umount Commit b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") moved ext4_unregister_sysfs() before flushing s_sb_upd_work to prevent new error work from being queued via /proc/fs/ext4/xx/mb_groups reads during unmount. However, this introduced a use-after-free because update_super_work calls ext4_notify_error_sysfs() -> sysfs_notify() which accesses the kobject's kernfs_node after it has been freed by kobject_del() in ext4_unregister_sysfs(): update_super_work ext4_put_super ----------------- -------------- ext4_unregister_sysfs(sb) kobject_del(&sbi->s_kobj) __kobject_del() sysfs_remove_dir() kobj->sd = NULL sysfs_put(sd) kernfs_put() // RCU free ext4_notify_error_sysfs(sbi) sysfs_notify(&sbi->s_kobj) kn = kobj->sd // stale pointer kernfs_get(kn) // UAF on freed kernfs_node ext4_journal_destroy() flush_work(&sbi->s_sb_upd_work) Instead of reordering the teardown sequence, fix this by making ext4_notify_error_sysfs() detect that sysfs has already been torn down by checking s_kobj.state_in_sysfs, and skipping the sysfs_notify() call in that case. A dedicated mutex (s_error_notify_mutex) serializes ext4_notify_error_sysfs() against kobject_del() in ext4_unregister_sysfs() to prevent TOCTOU races where the kobject could be deleted between the state_in_sysfs check and the sysfs_notify() call. Fixes: b98535d09179 ("ext4: fix bug_on in start_this_handle during umount filesystem") Cc: Jiayuan Chen <jiayuan.chen@linux.dev> Suggested-by: Jan Kara <jack@suse.cz> Signed-off-by: Jiayuan Chen <jiayuan.chen@shopee.com> Reviewed-by: Ritesh Harjani (IBM) <ritesh.list@gmail.com> Reviewed-by: Jan Kara <jack@suse.cz> Link: https://patch.msgid.link/20260319120336.157873-1-jiayuan.chen@linux.dev Signed-off-by: Theodore Ts'o <tytso@mit.edu> Cc: stable@kernel.org
2026-03-19 20:03:35 +08:00