[<prev] [next>] [<thread-prev] [day] [month] [year] [list]
Message-ID: <Y/1wyrjMOI/f5O/Q@xpf.sh.intel.com>
Date: Tue, 28 Feb 2023 11:11:06 +0800
From: Pengfei Xu <pengfei.xu@...el.com>
To: Jason Gunthorpe <jgg@...pe.ca>
CC: <baolu.lu@...el.com>, <yi.l.liu@...el.com>, <kevin.tian@...el.com>,
<heng.su@...el.com>, <linux-kernel@...r.kernel.org>
Subject: Re: [Syzkaller & bisect] There was "iommufd_test" WARNING in v6.2 in
guest
Hi Jason,
On 2023-02-27 at 14:03:56 +0800, Pengfei Xu wrote:
> Hi Jason,
>
> On 2023-02-24 at 10:48:45 -0400, Jason Gunthorpe wrote:
> > On Fri, Feb 24, 2023 at 01:43:38PM +0800, Pengfei Xu wrote:
> > > Hi Jason,
> > >
> > > Greeting!
> > >
> > > Platform: ADL-S and x86 platforms
> > > Host kernel 6.2.0-rc7 which doesn't enable iommufd by host kconfig setting as
> > > below:
> > > "# CONFIG_IOMMUFD is not set"
> > >
> > > Guest kconfig with iommufd enabled: https://github.com/xupengfe/syzkaller_logs/blob/main/230224_044002_iommufd_test/kconfig_origin
> > > Reproduced code: https://github.com/xupengfe/syzkaller_logs/blob/main/230224_044002_iommufd_test/repro.c
> > > v6.2 problem dmesg: https://github.com/xupengfe/syzkaller_logs/blob/main/230224_044002_iommufd_test/v6.2_c9c3395d5e3dcc6daee66c6908354d47bf98cb0c_dmesg.log
> > > Bisect info: https://github.com/xupengfe/syzkaller_logs/blob/main/230224_044002_iommufd_test/bisect_info.log
> > >
> > > There was "iommufd_test" WARNING in v6.2 in guest:
> > > [ 32.012827] ------------[ cut here ]------------
> > > [ 32.013027] WARNING: CPU: 1 PID: 393 at drivers/iommu/iommufd/selftest.c:403 iommufd_test+0xb19/0x16f0
> > > [ 32.013410] Modules linked in:
> >
> > I didn't include the IOMMU_TEST_OP_MD_CHECK_REFS in the syzkaller
> > descriptions, how did you hit this?
> >
> I am new to iommufd feature, and I'm not sure how syzkaller got to this
> unexpected test point.
>
> Anyway, I provided syzkaller repo top commit id info on that ADL-S:
> commit bcdf85f8bd3fccff5bc9507a589c4847d9b35405 (HEAD -> master)
> Author: Dmitry Vyukov <dvyukov@...gle.com>
> Date: Fri Feb 17 09:58:24 2023 +0100
> dashboard/config/linux: enable DWARF4 for all
>
> And I didn't change the file "syzkaller/sys/linux/dev_iommu.txt.const":
...
>
> > Anyhow, it is a small issue in the test suite because uptr + length overflows:
> >
> Thanks a lot for your patch! I'm glad it's helpful.
>
> Thanks!
> BR.
>
> > --- a/drivers/iommu/iommufd/selftest.c
> > +++ b/drivers/iommu/iommufd/selftest.c
> > @@ -568,13 +568,17 @@ static int iommufd_test_md_check_refs(struct iommufd_ucmd *ucmd,
> > void __user *uptr, size_t length,
> > unsigned int refs)
> > {
> > - if (length % PAGE_SIZE || (uintptr_t)uptr % PAGE_SIZE)
> > + uintptr_t end;
> > +
> > + if (length % PAGE_SIZE || (uintptr_t)uptr % PAGE_SIZE ||
> > + check_add_overflow((uintptr_t)uptr, (uintptr_t)length, &end))
> > return -EINVAL;
> >
I tested above patch on top of v6.2 kernel, there was no iommufd_test issue.
This issue was fixed.
Attached is the fixed dmesg log.
Thanks!
BR.
> > Jason
View attachment "v6.2_iommufd_test_fixed.log" of type "text/plain" (112320 bytes)
Powered by blists - more mailing lists