Re: [PATCH] ext4: Fix timer use-after-free on failed mount

On Mon, Mar 15, 2021 at 05:59:06PM +0100, Jan Kara wrote:

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 jack@suse.cz

Thanks, applied.

- Ted