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Baokun Li c7d10fa7d7 cachefiles: fix dentry leak in cachefiles_open_file() 
commit da6ef2dffe upstream.

A dentry leak may be caused when a lookup cookie and a cull are concurrent:

            P1             |             P2
-----------------------------------------------------------
cachefiles_lookup_cookie
  cachefiles_look_up_object
    lookup_one_positive_unlocked
     // get dentry
                            cachefiles_cull
                              inode->i_flags |= S_KERNEL_FILE;
    cachefiles_open_file
      cachefiles_mark_inode_in_use
        __cachefiles_mark_inode_in_use
          can_use = false
          if (!(inode->i_flags & S_KERNEL_FILE))
            can_use = true
	  return false
        return false
        // Returns an error but doesn't put dentry

After that the following WARNING will be triggered when the backend folder
is umounted:

==================================================================
BUG: Dentry 000000008ad87947{i=7a,n=Dx_1_1.img}  still in use (1) [unmount of ext4 sda]
WARNING: CPU: 4 PID: 359261 at fs/dcache.c:1767 umount_check+0x5d/0x70
CPU: 4 PID: 359261 Comm: umount Not tainted 6.6.0-dirty #25
RIP: 0010:umount_check+0x5d/0x70
Call Trace:
 <TASK>
 d_walk+0xda/0x2b0
 do_one_tree+0x20/0x40
 shrink_dcache_for_umount+0x2c/0x90
 generic_shutdown_super+0x20/0x160
 kill_block_super+0x1a/0x40
 ext4_kill_sb+0x22/0x40
 deactivate_locked_super+0x35/0x80
 cleanup_mnt+0x104/0x160
==================================================================

Whether cachefiles_open_file() returns true or false, the reference count
obtained by lookup_positive_unlocked() in cachefiles_look_up_object()
should be released.

Therefore release that reference count in cachefiles_look_up_object() to
fix the above issue and simplify the code.

Fixes: 1f08c925e7 ("cachefiles: Implement backing file wrangling")
Cc: stable@kernel.org
Signed-off-by: Baokun Li <libaokun1@huawei.com>
Link: https://lore.kernel.org/r/20240829083409.3788142-1-libaokun@huaweicloud.com
Acked-by: David Howells <dhowells@redhat.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2024-10-10 11:57:57 +02:00
arch riscv: Fix kernel stack size when KASAN is enabled 2024-10-10 11:57:53 +02:00
block blk_iocost: fix more out of bound shifts 2024-10-10 11:57:24 +02:00
certs certs: Reference revocation list for all keyrings 2023-08-17 20:12:41 +00:00
crypto crypto: simd - Do not call crypto_alloc_tfm during registration 2024-10-10 11:57:26 +02:00
Documentation arm64: Subscribe Microsoft Azure Cobalt 100 to erratum 3194386 2024-10-10 11:57:52 +02:00
drivers Input: adp5589-keys - fix adp5589_gpio_get_value() 2024-10-10 11:57:57 +02:00
fs cachefiles: fix dentry leak in cachefiles_open_file() 2024-10-10 11:57:57 +02:00
include media: uapi/linux/cec.h: cec_msg_set_reply_to: zero flags 2024-10-10 11:57:54 +02:00
init rust: fix the default format for CONFIG_{RUSTC,BINDGEN}_VERSION_TEXT 2024-08-29 17:33:29 +02:00
io_uring io_uring/sqpoll: do not put cpumask on stack 2024-10-04 16:29:44 +02:00
ipc sysctl: treewide: drop unused argument ctl_table_root::set_ownership(table) 2024-08-11 12:47:13 +02:00
kernel resource: fix region_intersects() vs add_memory_driver_managed() 2024-10-10 11:57:50 +02:00
lib mm/filemap: optimize filemap folio adding 2024-10-04 16:30:02 +02:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm mm: krealloc: consider spare memory for __GFP_ZERO 2024-10-10 11:57:50 +02:00
net gso: fix udp gso fraglist segmentation after pull from frag_list 2024-10-10 11:57:56 +02:00
rust rust: sync: require T: Sync for LockedBy::access 2024-10-10 11:57:44 +02:00
samples samples/bpf: Fix compilation errors with cf-protection option 2024-10-04 16:29:19 +02:00
scripts scripts: kconfig: merge_config: config files: add a trailing newline 2024-09-18 19:24:05 +02:00
security tomoyo: fallback to realpath if symlink's pathname does not exist 2024-10-10 11:57:57 +02:00
sound ALSA: hda/realtek: Add a quirk for HP Pavilion 15z-ec200 2024-10-10 11:57:46 +02:00
tools perf hist: Update hist symbol when updating maps 2024-10-10 11:57:52 +02:00
usr initramfs: Encode dependency on KBUILD_BUILD_TIMESTAMP 2023-06-06 17:54:49 +09:00
virt KVM: Use dedicated mutex to protect kvm_usage_count to avoid deadlock 2024-10-04 16:29:47 +02:00
.clang-format iommu: Add for_each_group_device() 2023-05-23 08:15:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore Remove *.orig pattern from .gitignore 2024-10-04 16:29:44 +02:00
.mailmap 20 hotfixes. 12 are cc:stable and the remainder address post-6.5 issues 2023-10-24 09:52:16 -10:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS USB: Remove Wireless USB and UWB documentation 2023-08-09 14:17:32 +02:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS membarrier: riscv: Add full memory barrier in switch_mm() 2024-09-12 11:11:45 +02:00
Makefile Linux 6.6.54 2024-10-04 16:30:05 +02:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.