From: Jason Gunthorpe <jgg@ziepe.ca>
To: syzbot <syzbot+2a4570d89a1e13003dbf@syzkaller.appspotmail.com>
Cc: iommu@lists.linux.dev, joro@8bytes.org,
linux-kernel@vger.kernel.org, robin.murphy@arm.com,
syzkaller-bugs@googlegroups.com, will@kernel.org
Subject: Re: [syzbot] [iommu?] WARNING in iommu_setup_default_domain
Date: Fri, 23 Oct 2026 10:34:02 -0300 [thread overview]
Message-ID: <20261023133402.GJ3381610@ziepe.ca> (raw)
In-Reply-To: <6ad19ce4.7952420f.283480.01c3.GAE@google.com>
On Thu, Oct 15, 2026 at 08:41:24PM -0700, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit: b88c841d1164 Merge tag 'input-for-v7.3-rc6' of git://git.k..
> git tree: upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=117d540d580000
> kernel config: https://syzkaller.appspot.com/x/.config?x=44ac479246d4559b
> dashboard link: https://syzkaller.appspot.com/bug?extid=2a4570d89a1e13003dbf
> compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44
> userspace arch: i386
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-b88c841d.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/e27770b53aa6/vmlinux-b88c841d.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/3a314a5eb19d/bzImage-b88c841d.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+2a4570d89a1e13003dbf@syzkaller.appspotmail.com
>
> R10: 0000000000000000 R11: 0000000000000292 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> </TASK>
> ------------[ cut here ]------------
> ret
> WARNING: drivers/iommu/iommu.c:3205 at iommu_setup_default_domain+0xbb6/0xf30 drivers/iommu/iommu.c:3205, CPU#2: syz.2.802/11603
> Modules linked in:
This is from a fault injection hit in the intel driver..
[ 382.158650][T11603] FAULT_INJECTION: forcing a failure.
[ 382.158650][T11603] name failslab, interval 1, probability 0, space 0, times 0
[..]
[ 382.158831][T11603] ? lockdep_hardirqs_on+0x7d/0x110
[ 382.158850][T11603] ? _raw_spin_unlock_irqrestore+0x3b/0x80
[ 382.158869][T11603] cache_tag_assign_domain+0x1f3/0x650
[ 382.158888][T11603] intel_iommu_attach_device+0x706/0xe00
[ 382.158906][T11603] ? __pfx_intel_iommu_attach_device+0x10/0x10
[ 382.158921][T11603] __iommu_attach_device+0x73/0x340
[ 382.158935][T11603] __iommu_device_set_domain+0x178/0x250
[ 382.158951][T11603] __iommu_group_set_domain_internal+0x1b1/0x450
[ 382.158969][T11603] iommu_setup_default_domain+0xb9b/0xf30
[ 382.158990][T11603] __iommu_probe_device+0x1174/0x1550
[ 382.159007][T11603] ? __pfx___iommu_probe_device+0x10/0x10
[ 382.159029][T11603] iommu_probe_device+0x28/0x130
[ 382.159045][T11603] iommu_bus_notifier+0x5b/0x110
[ 382.159061][T11603] notifier_call_chain+0x99/0x3f0
Which causes initial domain attach to fail:
/*
* Drivers are not allowed to fail the first domain attach.
* The only way to recover from this is to fail attaching the
* iommu driver and call ops->release_device. Put the domain
* in group->default_domain so it is freed after.
*/
ret = __iommu_group_set_domain_internal(
group, dom, IOMMU_SET_DOMAIN_MUST_SUCCEED);
if (WARN_ON(ret))
goto out_free_old;
Which we can't handle in any sane way.
Not sure what to do about this, it doesn't seem like a real bug to
worry about.
Jason
prev parent reply other threads:[~2026-10-23 13:34 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-16 3:41 syzbot
2026-10-23 13:34 ` Jason Gunthorpe [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20261023133402.GJ3381610@ziepe.ca \
--to=jgg@ziepe.ca \
--cc=iommu@lists.linux.dev \
--cc=joro@8bytes.org \
--cc=linux-kernel@vger.kernel.org \
--cc=robin.murphy@arm.com \
--cc=syzbot+2a4570d89a1e13003dbf@syzkaller.appspotmail.com \
--cc=syzkaller-bugs@googlegroups.com \
--cc=will@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox
all inboxes | Powered by JetHome®