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| author | Xiaxi Shen <shenxiaxi26@gmail.com> | 2024-07-14 21:33:36 -0700 |
|---|---|---|
| committer | Theodore Ts'o <tytso@mit.edu> | 2024-08-26 21:20:57 -0400 |
| commit | 0ce160c5bdb67081a62293028dc85758a8efb22a (patch) | |
| tree | 968ea990521a3da476706e0b69af411f3b2202c6 /fs/ext4 | |
| parent | ext4: use seq_putc() in two functions (diff) | |
| download | linux-0ce160c5bdb67081a62293028dc85758a8efb22a.tar.gz linux-0ce160c5bdb67081a62293028dc85758a8efb22a.zip | |
ext4: fix timer use-after-free on failed mount
Syzbot has found an ODEBUG bug in ext4_fill_super
The del_timer_sync function cancels the s_err_report timer,
which reminds about filesystem errors daily. We should
guarantee the timer is no longer active before kfree(sbi).
When filesystem mounting fails, the flow goes to failed_mount3,
where an error occurs when ext4_stop_mmpd is called, causing
a read I/O failure. This triggers the ext4_handle_error function
that ultimately re-arms the timer,
leaving the s_err_report timer active before kfree(sbi) is called.
Fix the issue by canceling the s_err_report timer after calling ext4_stop_mmpd.
Signed-off-by: Xiaxi Shen <shenxiaxi26@gmail.com>
Reported-and-tested-by: syzbot+59e0101c430934bc9a36@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=59e0101c430934bc9a36
Link: https://patch.msgid.link/20240715043336.98097-1-shenxiaxi26@gmail.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Cc: stable@kernel.org
Diffstat (limited to 'fs/ext4')
| -rw-r--r-- | fs/ext4/super.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index 7806044ed816..99ecd4ac7be0 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -5621,8 +5621,8 @@ failed_mount3a: failed_mount3: /* flush s_sb_upd_work before sbi destroy */ flush_work(&sbi->s_sb_upd_work); - del_timer_sync(&sbi->s_err_report); ext4_stop_mmpd(sbi); + del_timer_sync(&sbi->s_err_report); ext4_group_desc_free(sbi); failed_mount: if (sbi->s_chksum_driver) |