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Subject: Re: [syzbot] general protection fault in hrtimer_start_range_ns
To:     Thomas Gleixner <tglx@linutronix.de>,
        syzbot <syzbot+b935db3fe409625cca1b@syzkaller.appspotmail.com>,
        linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com,
        io-uring@vger.kernel.org
References: <0000000000009eeadd05cb511b60@google.com> <875yvbf23g.ffs@tglx>
From:   Jens Axboe <axboe@kernel.dk>
Message-ID: <8bbede01-4a97-bf22-92ad-c05a562c9799@kernel.dk>
Date:   Wed, 8 Sep 2021 11:02:56 -0600
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On 9/8/21 10:45 AM, Thomas Gleixner wrote:
> On Mon, Sep 06 2021 at 03:28, syzbot wrote:
>> syzbot found the following issue on:
>>
>> HEAD commit:    835d31d319d9 Merge tag 'media/v5.15-1' of git://git.kernel..
>> git tree:       upstream
>> console output: https://syzkaller.appspot.com/x/log.txt?x=14489886300000
>> kernel config:  https://syzkaller.appspot.com/x/.config?x=d793523866f2daea
>> dashboard link: https://syzkaller.appspot.com/bug?extid=b935db3fe409625cca1b
>> compiler:       Debian clang version 11.0.1-2, GNU ld (GNU Binutils for Debian) 2.35.1
>>
>> Unfortunately, I don't have any reproducer for this issue yet.
>>
>> IMPORTANT: if you fix the issue, please add the following tag to the commit:
>> Reported-by: syzbot+b935db3fe409625cca1b@syzkaller.appspotmail.com
>>
>> general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
>> KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
>> CPU: 0 PID: 12936 Comm: iou-sqp-12929 Not tainted 5.14.0-syzkaller #0
>> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
>> RIP: 0010:lock_hrtimer_base kernel/time/hrtimer.c:173 [inline]
> 
> That's almost certainly deferencing hrtimer->base and as that is NULL
> this looks like a not initialized hrtimer.

Does certainly look like that, I'll take a look. And agree the next one
looks like the same thing.

-- 
Jens Axboe