From: Eduard Zingerman <eddyz87@gmail.com>
To: yonghong.song@linux.dev,
syzbot <syzbot+d61b595e9205573133b3@syzkaller.appspotmail.com>,
andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
daniel@iogearbox.net, davem@davemloft.net, haoluo@google.com,
hawk@kernel.org, john.fastabend@gmail.com, jolsa@kernel.org,
kpsingh@kernel.org, kuba@kernel.org,
linux-kernel@vger.kernel.org, martin.lau@linux.dev,
netdev@vger.kernel.org, sdf@google.com, song@kernel.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [syzbot] [bpf?] KMSAN: uninit-value in ieee802154_subif_start_xmit
Date: Mon, 07 Aug 2023 16:48:40 +0300 [thread overview]
Message-ID: <74c9a88d79b7c65e2fdc2dc1609e13590225cb60.camel@gmail.com> (raw)
In-Reply-To: <9c8f04a0bf90db4bb8e6192824ab71f58244b74b.camel@gmail.com>
On Mon, 2023-08-07 at 16:11 +0300, Eduard Zingerman wrote:
[...]
> $ bpftool prog dump jited id <some-id>
> bpf_prog_ebeed182d92b487f:
> 0: nopl (%rax,%rax)
> 5: nop
> 7: pushq %rbp
> 8: movq %rsp, %rbp
> b: subq $8, %rsp
> 12: movl $553656332, -8(%rbp)
> 19: movswq %bp, %rdi ; <---- Note movswq %bp !
> 1d: addq $-8, %rdi
> 21: movl $3, %esi
> 26: cmpq %rdi, %rsi
> 29: jbe 0x2b
> 2b: callq 0xffffffffe11c484c
> 30: xorl %eax, %eax
> 32: leave
> 33: retq
>
> Note jit instruction #19 corresponding to BPF instruction #1, which
> loads truncated and sign-extended value of %rbp's first byte as an
> address of format string.
Correction: sign-extended value of %rbp's first *two* bytes,
disassembly with opcodes:
19: movswq %bp, %rdi
48 0f bf fd
[...]
next prev parent reply other threads:[~2023-08-07 13:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-08-06 23:23 [syzbot] [bpf?] KMSAN: uninit-value in ieee802154_subif_start_xmit syzbot
2023-08-07 6:40 ` Yonghong Song
2023-08-07 13:11 ` Eduard Zingerman
2023-08-07 13:48 ` Eduard Zingerman [this message]
2023-08-07 14:40 ` Yonghong Song
2023-08-07 14:45 ` Eduard Zingerman
2023-08-07 18:09 ` Yonghong Song
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