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Message-ID: <2ee098ec-a46f-44fa-8719-049331c4c206@linux.dev>
Date: Mon, 1 Apr 2024 11:55:17 -0700
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Subject: Re: [syzbot] [bpf?] KMSAN: uninit-value in trie_delete_elem
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To: 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>
From: Yonghong Song <yonghong.song@linux.dev>
In-Reply-To: <000000000000f9ce6d061494e694@google.com>
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On 3/26/24 12:00 PM, syzbot wrote:
> Hello,
>
> syzbot found the following issue on:
>
> HEAD commit:    4f55aa85a874 Merge tag 'fbdev-for-6.9-rc1' of git://git.ke..
> git tree:       upstream
> console output: https://syzkaller.appspot.com/x/log.txt?x=11a8dc6e180000
> kernel config:  https://syzkaller.appspot.com/x/.config?x=e6bd769cb793b98a
> dashboard link: https://syzkaller.appspot.com/bug?extid=603bcd9b0bf1d94dbb9b
> compiler:       Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
> userspace arch: i386
>
> Unfortunately, I don't have any reproducer for this issue yet.
>
> Downloadable assets:
> disk image: https://storage.googleapis.com/syzbot-assets/991fcbce770a/disk-4f55aa85.raw.xz
> vmlinux: https://storage.googleapis.com/syzbot-assets/bd716e5d2c3c/vmlinux-4f55aa85.xz
> kernel image: https://storage.googleapis.com/syzbot-assets/bf1151dbf5fc/bzImage-4f55aa85.xz
>
> IMPORTANT: if you fix the issue, please add the following tag to the commit:
> Reported-by: syzbot+603bcd9b0bf1d94dbb9b@syzkaller.appspotmail.com
>
> =====================================================
> 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?