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Changes since last update: 

- Fix use-after-free of the on-stack z_erofs_decompressqueue;
 
  - Fix sysfs documentation Sphinx warnings.
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Merge tag 'erofs-for-5.18-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs

Pull erofs fixes from Gao Xiang:
 "One patch to fix a use-after-free race related to the on-stack
  z_erofs_decompressqueue, which happens very rarely but needs to be
  fixed properly soon.

  The other patch fixes some sysfs Sphinx warnings"

* tag 'erofs-for-5.18-rc4-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/xiang/erofs:
  Documentation/ABI: sysfs-fs-erofs: Fix Sphinx errors
  erofs: fix use-after-free of on-stack io[]
This commit is contained in:
Linus Torvalds 2022-04-20 12:35:20 -07:00
parent 906f904097 8b1ac84dcf
commit 10c5f102e2
3 changed files with 8 additions and 11 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
Documentation/ABI/testing/sysfs-fs-erofs
View File

@ -9,8 +9,9 @@ Description: Shows all enabled kernel features.
What: /sys/fs/erofs/<disk>/sync_decompress
Date: November 2021
Contact: "Huang Jianan" <huangjianan@oppo.com>
Description: Control strategy of sync decompression
Description: Control strategy of sync decompression:
- 0 (default, auto): enable for readpage, and enable for
readahead on atomic contexts only,
readahead on atomic contexts only.
- 1 (force on): enable for readpage and readahead.
- 2 (force off): disable for all situations.

12
fs/erofs/zdata.c
View File

@ -1066,12 +1066,9 @@ static void z_erofs_decompress_kickoff(struct z_erofs_decompressqueue *io,
/* wake up the caller thread for sync decompression */
if (sync) {
unsigned long flags;
spin_lock_irqsave(&io->u.wait.lock, flags);
if (!atomic_add_return(bios, &io->pending_bios))
wake_up_locked(&io->u.wait);
spin_unlock_irqrestore(&io->u.wait.lock, flags);
complete(&io->u.done);
return;
}
@ -1217,7 +1214,7 @@ jobqueue_init(struct super_block *sb,
} else {
fg_out:
q = fgq;
init_waitqueue_head(&fgq->u.wait);
init_completion(&fgq->u.done);
atomic_set(&fgq->pending_bios, 0);
}
q->sb = sb;
@ -1419,8 +1416,7 @@ static void z_erofs_runqueue(struct super_block *sb,
return;
/* wait until all bios are completed */
io_wait_event(io[JQ_SUBMIT].u.wait,
!atomic_read(&io[JQ_SUBMIT].pending_bios));
wait_for_completion_io(&io[JQ_SUBMIT].u.done);
/* handle synchronous decompress queue in the caller context */
z_erofs_decompress_queue(&io[JQ_SUBMIT], pagepool);

2
fs/erofs/zdata.h
View File

@ -97,7 +97,7 @@ struct z_erofs_decompressqueue {
z_erofs_next_pcluster_t head;
union {
wait_queue_head_t wait;
struct completion done;
struct work_struct work;
} u;
};