Re: [syzbot] [bpf?] KMSAN: uninit-value in trie_delete_elem

[Yonghong Song]

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@xxxxxxxxxxxxxxxxxxxxxxxxx
>
> =====================================================
> 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?