From 2a4ae3bcdf05b8639406eaa09a2939f3c6dd8e75 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Mon, 15 Mar 2021 17:59:06 +0100 Subject: ext4: fix timer use-after-free on failed mount When filesystem mount fails because of corrupted filesystem we first cancel the s_err_report timer reminding fs errors every day and only then we flush s_error_work. However s_error_work may report another fs error and re-arm timer thus resulting in timer use-after-free. Fix the problem by first flushing the work and only after that canceling the s_err_report timer. Reported-by: syzbot+628472a2aac693ab0fcd@syzkaller.appspotmail.com Fixes: 2d01ddc86606 ("ext4: save error info to sb through journal if available") CC: stable@vger.kernel.org Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20210315165906.2175-1-jack@suse.cz Signed-off-by: Theodore Ts'o --- fs/ext4/super.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'fs/ext4') diff --git a/fs/ext4/super.c b/fs/ext4/super.c index a0a256859662..b9693680463a 100644 --- a/fs/ext4/super.c +++ b/fs/ext4/super.c @@ -5154,8 +5154,8 @@ failed_mount_wq: failed_mount3a: ext4_es_unregister_shrinker(sbi); failed_mount3: - del_timer_sync(&sbi->s_err_report); flush_work(&sbi->s_error_work); + del_timer_sync(&sbi->s_err_report); if (sbi->s_mmp_tsk) kthread_stop(sbi->s_mmp_tsk); failed_mount2: -- cgit v1.2.3