From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Andrey Konovalov <andreyknvl@gmail.com>,
Dmitry Vyukov <dvyukov@google.com>
Cc: syzbot <syzbot+9ce030d4c89856b27619@syzkaller.appspotmail.com>,
LKML <linux-kernel@vger.kernel.org>,
syzkaller-bugs <syzkaller-bugs@googlegroups.com>,
"open list:HID CORE LAYER" <linux-input@vger.kernel.org>
Subject: Re: [syzbot] unexpected kernel reboot (4)
Date: Thu, 15 Apr 2021 01:16:13 +0900 [thread overview]
Message-ID: <b8162e95-fb2e-51f6-9d9b-a4d64873876e@i-love.sakura.ne.jp> (raw)
In-Reply-To: <CA+fCnZcWEuYeOx6-0LY+cqtGVbMx2OiyhEELErdfwaHGcUWHbQ@mail.gmail.com>
On 2021/04/15 0:39, Andrey Konovalov wrote:
> On Wed, Apr 14, 2021 at 7:45 AM Dmitry Vyukov <dvyukov@google.com> wrote:
>>
>> On Tue, Apr 13, 2021 at 11:27 PM syzbot
>> <syzbot+9ce030d4c89856b27619@syzkaller.appspotmail.com> wrote:
>>>
>>> Hello,
>>>
>>> syzbot found the following issue on:
>>>
>>> HEAD commit: 89698bec Merge tag 'm68knommu-for-v5.12-rc7' of git://git...
>>> git tree: upstream
>>> console output: https://syzkaller.appspot.com/x/log.txt?x=1243fcfed00000
>>> kernel config: https://syzkaller.appspot.com/x/.config?x=b234ddbbe2953747
>>> dashboard link: https://syzkaller.appspot.com/bug?extid=9ce030d4c89856b27619
>>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=173e92fed00000
>>> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1735da2ed00000
>>>
>>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>>> Reported-by: syzbot+9ce030d4c89856b27619@syzkaller.appspotmail.com
>>>
>>> output_len: 0x000000000e74eb68
>>> kernel_total_size: 0x000000000f226000
>>> needed_size: 0x000000000f400000
>>> trampoline_32bit: 0x000000000009d000
>>> Decompressing Linux... Parsing ELF... done.
>>> Booting the kernel.
>>
>> +linux-input
>>
>> The reproducer connects some USB HID device and communicates with the driver.
>> Previously we observed reboots because HID devices can trigger reboot
>> SYSRQ, but we disable it with "CONFIG_MAGIC_SYSRQ is not set".
>> How else can a USB device reboot the machine? Is it possible to disable it?
>> I don't see any direct includes of <linux/reboot.h> in drivers/usb/*
>
> This happens when a keyboard sends the Ctrl+Alt+Del sequence, see
> fn_boot_it()->ctrl_alt_del() in drivers/tty/vt/keyboard.c.
>
> There was a patchset by Tetsuo [1] to suppress this, but I think it
> was abandoned.
Not abandoned; I'm waiting for you to join the discussion.
But for right now I'm trying to merge LOCKDEP's capacity tuning patch for
https://github.com/google/syzkaller/pull/2535 in the next merge window.
I still believe that ctrl_alt_del() etc. should be initially controlled
via kernel config options (despite Linus's objection at
https://lore.kernel.org/lkml/CAHk-=wgz=7MGxxX-tmMmdCsKyYJkuyxNc-4uLP=e_eEV=OzUaw@mail.gmail.com/ ), for
we will need several trials and errors (and an effort to avoid kernel size bloating
like https://lkml.kernel.org/r/YD57hjaSmsYapHnQ@alley still remains) before we can
determine usable units for allow toggling via kernel command line options.
>
> (This reminds of a somewhat related syzkaller issue:
> https://github.com/google/syzkaller/issues/1824; it relies on a
> similar reproducer.)
>
> [1] https://groups.google.com/g/syzkaller/c/7wCmrGlLgm0/m/5yG6HVtbBQAJ
>
next prev parent reply other threads:[~2021-04-14 16:16 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <000000000000301a4d05bfe14b8f@google.com>
2021-04-14 5:45 ` [syzbot] unexpected kernel reboot (4) Dmitry Vyukov
2021-04-14 15:39 ` Andrey Konovalov
2021-04-14 16:16 ` Tetsuo Handa [this message]
2021-04-22 10:16 ` Tetsuo Handa
2021-04-22 14:20 ` Dmitry Vyukov
2021-04-22 16:13 ` Tetsuo Handa
2021-04-22 17:00 ` Dmitry Vyukov
2021-04-17 3:19 ` Tetsuo Handa
2021-04-18 15:09 ` Tetsuo Handa
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