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From: Aleksandr Nogikh <nogikh@google.com>
Date: Wed, 3 Apr 2024 10:47:03 +0200
Message-ID: <CANp29Y7WXm58E=Dv5WFivKuSz-OSCjMQLhBVdPA=ZpNmwcMitg@mail.gmail.com>
Subject: Re: [syzbot] [bpf?] KMSAN: uninit-value in trie_delete_elem
To: Yonghong Song <yonghong.song@linux.dev>
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
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On Wed, Apr 3, 2024 at 5:59=E2=80=AFAM Yonghong Song <yonghong.song@linux.d=
ev> wrote:
>
>
> On 4/1/24 11:36 PM, Aleksandr Nogikh wrote:
> > Hi,
> >
> > On Mon, Apr 1, 2024 at 8:55=E2=80=AFPM Yonghong Song <yonghong.song@lin=
ux.dev> wrote:
> >>
> >> On 3/26/24 12:00 PM, syzbot wrote:
> >>> Hello,
> >>>
> >>> syzbot found the following issue on:
> >>>
> >>> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D
> >>> BUG: KMSAN: uninit-value in trie_delete_elem+0xc0/0xbe0 kernel/bpf/lp=
m_trie.c:448
> >> Unrelated to the bug itself, with KMSAN is enabled, qemu cannot boot m=
y vm
> >> any more. Anything special I need to do in order to boot a KMSAN kerne=
l?
> >>
> > 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.

--=20
Aleksandr