From: Xiaxi Shen shenxiaxi26@gmail.com
mainline inclusion from mainline-v6.12-rc1 commit 0ce160c5bdb67081a62293028dc85758a8efb22a category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAYRD8 CVE: CVE-2024-49960
Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?i...
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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 We should guarantee the timer is no longer active before kfree(sbi).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 Conflicts: fs/ext4/super.c [Context differences.] Signed-off-by: Yongjian Sun sunyongjian1@huawei.com --- 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 a8c155cfdbf6..2adee3847415 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -5301,8 +5301,8 @@ failed_mount8: __maybe_unused failed_mount3: /* flush s_error_work before sbi destroy */ flush_work(&sbi->s_error_work); - del_timer_sync(&sbi->s_err_report); ext4_stop_mmpd(sbi); + del_timer_sync(&sbi->s_err_report); failed_mount2: rcu_read_lock(); group_desc = rcu_dereference(sbi->s_group_desc);