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fbed4baed0
When using the ioctl interface to resize a UBI volume, `ubi_resize_volume`
resizes the EBA table first but does not change `vol->reserved_pebs` in
the same atomic context, which may cause concurrent access to the EBA table.
For example, when a user shrinks UBI volume A by calling `ubi_resize_volume`,
while another thread is writing to volume B and triggering wear-leveling,
which may call `ubi_write_fastmap`, under these circumstances, KASAN may
report a slab-out-of-bounds error in `ubi_eba_get_ldesc+0xfb/0x130`.
This patch fixes race conditions in `ubi_resize_volume` and
`ubi_update_fastmap` to avoid out-of-bounds reads of `eba_tbl`. First,
it ensures that updates to `eba_tbl` and `reserved_pebs` are protected
by `vol->volumes_lock`. Second, it implements a rollback mechanism in case
of resize failure. It is also worth mentioning that for volume shrinkage
failures, since part of the volume has already been shrunk and unmapped,
there is no need to recover `{rsvd/avail}_pebs`.
==================================================================
BUG: KASAN: slab-out-of-bounds in ubi_eba_get_ldesc+0xfb/0x130 [ubi]
Read of size 4 at addr ffff88800f43f570 by task kworker/u16:0/7
CPU: 0 PID: 7 Comm: kworker/u16:0 Not tainted 5.16.0-rc7 #3
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
Workqueue: writeback wb_workfn (flush-ubifs_0_0)
Call Trace:
<TASK>
dump_stack_lvl+0x4d/0x66
print_address_description.constprop.0+0x41/0x60
kasan_report.cold+0x83/0xdf
ubi_eba_get_ldesc+0xfb/0x130 [ubi]
ubi_update_fastmap.cold+0x60f/0xc7d [ubi]
ubi_wl_get_peb+0x25b/0x4f0 [ubi]
try_write_vid_and_data+0x9a/0x4d0 [ubi]
ubi_eba_write_leb+0x7e4/0x17d0 [ubi]
ubi_leb_map+0x1a0/0x2c0 [ubi]
ubifs_leb_map+0x139/0x270 [ubifs]
ubifs_add_bud_to_log+0xb40/0xf30 [ubifs]
make_reservation+0x86e/0xb00 [ubifs]
ubifs_jnl_write_data+0x430/0x9d0 [ubifs]
do_writepage+0x1d1/0x550 [ubifs]
ubifs_writepage+0x37c/0x670 [ubifs]
__writepage+0x67/0x170
write_cache_pages+0x259/0xa90
do_writepages+0x277/0x5d0
__writeback_single_inode+0xb8/0x850
writeback_sb_inodes+0x4b3/0xb20
__writeback_inodes_wb+0xc1/0x220
wb_writeback+0x59f/0x740
wb_workfn+0x6d0/0xca0
process_one_work+0x711/0xfc0
worker_thread+0x95/0xd00
kthread+0x3a6/0x490
ret_from_fork+0x1f/0x30
</TASK>
Allocated by task 711:
kasan_save_stack+0x1e/0x50
__kasan_kmalloc+0x81/0xa0
ubi_eba_create_table+0x88/0x1a0 [ubi]
ubi_resize_volume.cold+0x175/0xae7 [ubi]
ubi_cdev_ioctl+0x57f/0x1a60 [ubi]
__x64_sys_ioctl+0x13a/0x1c0
do_syscall_64+0x35/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
Last potentially related work creation:
kasan_save_stack+0x1e/0x50
__kasan_record_aux_stack+0xb7/0xc0
call_rcu+0xd6/0x1000
blk_stat_free_callback+0x28/0x30
blk_release_queue+0x8a/0x2e0
kobject_put+0x186/0x4c0
scsi_device_dev_release_usercontext+0x620/0xbd0
execute_in_process_context+0x2f/0x120
device_release+0xa4/0x240
kobject_put+0x186/0x4c0
put_device+0x20/0x30
__scsi_remove_device+0x1c3/0x300
scsi_probe_and_add_lun+0x2140/0x2eb0
__scsi_scan_target+0x1f2/0xbb0
scsi_scan_channel+0x11b/0x1a0
scsi_scan_host_selected+0x24c/0x310
do_scsi_scan_host+0x1e0/0x250
do_scan_async+0x45/0x490
async_run_entry_fn+0xa2/0x530
process_one_work+0x711/0xfc0
worker_thread+0x95/0xd00
kthread+0x3a6/0x490
ret_from_fork+0x1f/0x30
The buggy address belongs to the object at ffff88800f43f500
which belongs to the cache kmalloc-128 of size 128
The buggy address is located 112 bytes inside of
128-byte region [ffff88800f43f500, ffff88800f43f580)
The buggy address belongs to the page:
page:ffffea00003d0f00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0xf43c
head:ffffea00003d0f00 order:2 compound_mapcount:0 compound_pincount:0
flags: 0x1fffff80010200(slab|head|node=0|zone=1|lastcpupid=0x1fffff)
raw: 001fffff80010200 ffffea000046ba08 ffffea0000457208 ffff88810004d1c0
raw: 0000000000000000 0000000000190019 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
Memory state around the buggy address:
ffff88800f43f400: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88800f43f480: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
> ffff88800f43f500: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 fc fc
^
ffff88800f43f580: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88800f43f600: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
The following steps can used to reproduce:
Process 1: write and trigger ubi wear-leveling
ubimkvol /dev/ubi0 -s 5000MiB -N v1
ubimkvol /dev/ubi0 -s 2000MiB -N v2
ubimkvol /dev/ubi0 -s 10MiB -N v3
mount -t ubifs /dev/ubi0_0 /mnt/ubifs
while true;
do
filename=/mnt/ubifs/$((RANDOM))
dd if=/dev/random of=${filename} bs=1M count=$((RANDOM % 1000))
rm -rf ${filename}
sync /mnt/ubifs/
done
Process 2: do random resize
struct ubi_rsvol_req req;
req.vol_id = 1;
req.bytes = (rand() % 50) * 512KB;
ioctl(fd, UBI_IOCRSVOL, &req);
V3:
- Fix the commit message error.
V2:
- Add volumes_lock in ubi_eba_copy_leb() to avoid race caused by
updating eba_tbl.
V1:
- Rebase the patch on the latest mainline.
Signed-off-by: Guo Xuenan <guoxuenan@huawei.com>
Signed-off-by: ZhaoLong Wang <wangzhaolong1@huawei.com>
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Signed-off-by: Richard Weinberger <richard@nod.at>
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Linux kernel
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