Messages in this thread | | | Date | Tue, 14 Jun 2022 16:50:22 +0800 | Subject | Re: [syzbot] KASAN: use-after-free Read in copy_page_from_iter_atomic (2) | From | Qu Wenruo <> |
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On 2022/6/14 15:17, Christoph Hellwig wrote: > 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?
The same way as data?
map-logical to find the location of a mirror, write 4 bytes of zero into the location, then call it a day.
Although for metadata, you may want to choose a metadata that would definitely get read. Thus tree root is a good candidate.
Thanks, Qu
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