| Message ID | 20240715043336.98097-1-shenxiaxi26@gmail.com |
|---|---|
| State | Awaiting Upstream |
| Headers | show |
| Series | ext4: Fix timer use-after-free on failed mount | expand |
On Sun, 14 Jul 2024 21:33:36 -0700, Xiaxi Shen wrote: > 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 guarantee the timer is no longer active before kfree(sbi).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. > > [...] Applied, thanks! [1/1] ext4: Fix timer use-after-free on failed mount commit: 0ce160c5bdb67081a62293028dc85758a8efb22a Best regards,
diff --git a/fs/ext4/super.c b/fs/ext4/super.c index c682fb927b64..1b4b0d3d8889 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -5626,8 +5626,8 @@ failed_mount8: __maybe_unused 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)
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 We should guarantee the timer is no longer active before kfree(sbi).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 --- fs/ext4/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)