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Message-ID: <110c4768-2294-436e-a96a-7063bae85ee7@linux.dev>
Date: Thu, 4 Apr 2024 12:00:11 -0700
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Subject: Re: [syzbot] [bpf?] KMSAN: uninit-value in trie_delete_elem
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To: Aleksandr Nogikh <nogikh@google.com>
Cc: Alexander Potapenko <glider@google.com>,
 syzbot <syzbot+603bcd9b0bf1d94dbb9b@syzkaller.appspotmail.com>,
 andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
 daniel@iogearbox.net, eddyz87@gmail.com, haoluo@google.com,
 john.fastabend@gmail.com, jolsa@kernel.org, kpsingh@kernel.org,
 linux-kernel@vger.kernel.org, martin.lau@linux.dev, sdf@google.com,
 song@kernel.org, syzkaller-bugs@googlegroups.com
References: <000000000000f9ce6d061494e694@google.com>
 <2ee098ec-a46f-44fa-8719-049331c4c206@linux.dev>
 <CANp29Y4WcXr7vd=cvdtxRWaPxOKzr97f9L+BXtm07AGGiW2j2A@mail.gmail.com>
 <02d29315-13ee-45c1-984e-13c98e88247b@linux.dev>
 <CANp29Y7WXm58E=Dv5WFivKuSz-OSCjMQLhBVdPA=ZpNmwcMitg@mail.gmail.com>
From: Yonghong Song <yonghong.song@linux.dev>
In-Reply-To: <CANp29Y7WXm58E=Dv5WFivKuSz-OSCjMQLhBVdPA=ZpNmwcMitg@mail.gmail.com>
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On 4/3/24 1:47 AM, Aleksandr Nogikh wrote:
> On Wed, Apr 3, 2024 at 5:59 AM Yonghong Song <yonghong.song@linux.dev> wrote:
>>
>> On 4/1/24 11:36 PM, Aleksandr Nogikh wrote:
>>> Hi,
>>>
>>> On Mon, Apr 1, 2024 at 8:55 PM Yonghong Song <yonghong.song@linux.dev> wrote:
>>>> On 3/26/24 12:00 PM, syzbot wrote:
>>>>> Hello,
>>>>>
>>>>> syzbot found the following issue on:
>>>>>
>>>>> =====================================================
>>>>> BUG: KMSAN: uninit-value in trie_delete_elem+0xc0/0xbe0 kernel/bpf/lpm_trie.c:448
>>>> Unrelated to the bug itself, with KMSAN is enabled, qemu cannot boot my vm
>>>> any more. Anything special I need to do in order to boot a KMSAN kernel?
>>>>
>>> Does the kernel print any specific errors to the serial console while
>>> booting? Or nothing at all?
>> In my case, nothing at all.
>>
> If you're using qemu, please try adding "-machine pc-q35-7.1" to its
> arguments. Otherwise it's known to have problems with very large
> kernel images.

I still do not help. My qemu does not support pc-q35-7.1. The most
q35 machine is pc-q35-5.2 and it does not work.