linux-kernel - Re: [syzbot] BUG: unable to handle kernel paging request in get

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Message-ID: <CACT4Y+Zb0T4bPk=gzYtexPqHTGSFAHaeY6DCYq268GV4+TM+gQ@mail.gmail.com>
Date:   Fri, 4 Nov 2022 09:28:02 -0700
From:   Dmitry Vyukov <dvyukov@...gle.com>
To:     Sean Christopherson <seanjc@...gle.com>
Cc:     syzbot <syzbot+ffb4f000dc2872c93f62@...kaller.appspotmail.com>,
        bp@...en8.de, brgerst@...il.com, dave.hansen@...ux.intel.com,
        hpa@...or.com, kirill@...temov.name, linux-kernel@...r.kernel.org,
        mingo@...hat.com, peterz@...radead.org,
        syzkaller-bugs@...glegroups.com, tglx@...utronix.de,
        thomas.lendacky@....com, x86@...nel.org
Subject: Re: [syzbot] BUG: unable to handle kernel paging request in get_desc

On Fri, 4 Nov 2022 at 08:28, 'Sean Christopherson' via syzkaller-bugs
<syzkaller-bugs@...glegroups.com> wrote:
>
> On Fri, Nov 04, 2022, syzbot wrote:
> > Hello,
> >
> > syzbot found the following issue on:
> >
> > HEAD commit:    81214a573d19 Add linux-next specific files for 20221103
> > git tree:       linux-next
> > console output: https://syzkaller.appspot.com/x/log.txt?x=132019de880000
> > kernel config:  https://syzkaller.appspot.com/x/.config?x=cdc625e9234bac0
> > dashboard link: https://syzkaller.appspot.com/bug?extid=ffb4f000dc2872c93f62
> > compiler:       gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
> > syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=12dd52ca880000
> >
> > Downloadable assets:
> > disk image: https://storage.googleapis.com/syzbot-assets/5d4dda497754/disk-81214a57.raw.xz
> > vmlinux: https://storage.googleapis.com/syzbot-assets/9658efff160a/vmlinux-81214a57.xz
> > kernel image: https://storage.googleapis.com/syzbot-assets/3711180f2565/bzImage-81214a57.xz
> >
> > IMPORTANT: if you fix the issue, please add the following tag to the commit:
> > Reported-by: syzbot+ffb4f000dc2872c93f62@...kaller.appspotmail.com
> >
> > BUG: unable to handle page fault for address: fffffbc5a1c22e00
> > #PF: supervisor read access in kernel mode
> > #PF: error_code(0x0000) - not-present page
> > PGD 23ffe4067 P4D 23ffe4067 PUD 13ff2d067 PMD 13ff2c067 PTE 0
> > Oops: 0000 [#1] PREEMPT SMP KASAN
> > CPU: 0 PID: 5368 Comm: syz-executor.2 Not tainted 6.1.0-rc3-next-20221103-syzkaller #0
> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/11/2022
> > RIP: 0010:get_desc+0x128/0x460 arch/x86/lib/insn-eval.c:660
>
> I'm pretty sure this is the same thing as
>
>   BUG: unable to handle kernel paging request in vmx_handle_exit_irqoff
>
> I'll verify and get a patch posted shortly.

This repro does not create any VMs, it's just:

iopl(0x3)
rt_sigreturn()

Do you still think it's related to the vmx_handle_exit_irqoff issue?