Re: [syzbot] KASAN: use-after-free Read in copy_page_from_iter_atomic (2)

Christoph Hellwig
2022-06-14T07:19:37Z

On Mon, Jun 13, 2022 at 09:39:12PM +0200, David Sterba wrote:
> On Fri, Jun 10, 2022 at 12:10:19AM -0700, syzbot wrote:
> > syzbot has bisected this issue to:
> >
> > commit 4cd4aed63125ccd4efc35162627827491c2a7be7
> > Author: Christoph Hellwig <hch@lst.de>
> > Date: Fri May 27 08:43:20 2022 +0000
> >
> > btrfs: fold repair_io_failure into btrfs_repair_eb_io_failure
>
> Josef also reported a crash and found a bug in the patch, now added as
> fixup that'll be in for-next:

The patch looks correct to me. Two things to note here:

- I hadn't realized you had queued up the series. I've actually
started to merge some of my bio work with the bio split at
submission time work from Qu and after a few iterations I think
I would do the repair code a bit differently based on that.
Can you just drop the series for now?
- I find it interesting that syzbot hits btrfs metadata repair.
xfstests seems to have no coverage and I could not come up with
a good idea how to properly test it. Does anyone have a good
idea on how to intentially corrupt metadata in a deterministic
way?