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 We should guarantee the timer is no longer active before kfree(sbi).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@xxxxxxxxx> Reported-and-tested-by: syzbot+59e0101c430934bc9a36@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://syzkaller.appspot.com/bug?extid=59e0101c430934bc9a36 --- fs/ext4/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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) -- 2.34.1
