From: Eduard Zingerman <eddyz87@gmail.com>
To: Brahmajit Das <listout@listout.xyz>
Cc: andrii@kernel.org, ast@kernel.org, bpf@vger.kernel.org,
daniel@iogearbox.net, haoluo@google.com,
john.fastabend@gmail.com, jolsa@kernel.org, kpsingh@kernel.org,
linux-kernel@vger.kernel.org, martin.lau@linux.dev,
sdf@fomichev.me, song@kernel.org,
syzbot+d36d5ae81e1b0a53ef58@syzkaller.appspotmail.com,
syzkaller-bugs@googlegroups.com, yonghong.song@linux.dev,
KaFai Wan <kafai.wan@linux.dev>
Subject: Re: [PATCH v4 1/2] bpf: Skip scalar adjustment for BPF_NEG if dst is a pointer
Date: Wed, 01 Oct 2025 12:32:11 -0700 [thread overview]
Message-ID: <8f72a29f419377ac9e3ddd7ae56bc1e0826058c6.camel@gmail.com> (raw)
In-Reply-To: <20251001191739.2323644-2-listout@listout.xyz>
On Thu, 2025-10-02 at 00:47 +0530, Brahmajit Das wrote:
> In check_alu_op(), the verifier currently calls check_reg_arg() and
> adjust_scalar_min_max_vals() unconditionally for BPF_NEG operations.
> However, if the destination register holds a pointer, these scalar
> adjustments are unnecessary and potentially incorrect.
>
> This patch adds a check to skip the adjustment logic when the destination
> register contains a pointer.
>
> Reported-by: syzbot+d36d5ae81e1b0a53ef58@syzkaller.appspotmail.com
> Closes: https://syzkaller.appspot.com/bug?extid=d36d5ae81e1b0a53ef58
> Fixes: aced132599b3 ("bpf: Add range tracking for BPF_NEG")
> Suggested-by: KaFai Wan <kafai.wan@linux.dev>
> Suggested-by: Eduard Zingerman <eddyz87@gmail.com>
> Signed-off-by: Brahmajit Das <listout@listout.xyz>
> ---
Acked-by: Eduard Zingerman <eddyz87@gmail.com>
[...]
next prev parent reply other threads:[~2025-10-01 19:32 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-23 9:02 [syzbot] [bpf?] general protection fault in print_reg_state syzbot
2025-09-23 16:41 ` [PATCH 1/1] bpf: fix NULL pointer dereference in print_reg_state() Brahmajit Das
2025-10-01 19:17 ` [PATCH v4 0/2] bpf: Fix verifier crash on BPF_NEG with pointer register Brahmajit Das
2025-10-01 19:17 ` [PATCH v4 1/2] bpf: Skip scalar adjustment for BPF_NEG if dst is a pointer Brahmajit Das
2025-10-01 19:32 ` Eduard Zingerman [this message]
2025-10-01 19:17 ` [PATCH v4 2/2] selftests/bpf: Add test for BPF_NEG alu on CONST_PTR_TO_MAP Brahmajit Das
2025-10-01 19:33 ` Eduard Zingerman
2025-10-01 21:10 ` [PATCH v4 0/2] bpf: Fix verifier crash on BPF_NEG with pointer register patchwork-bot+netdevbpf
2025-09-23 16:43 ` [PATCH 1/1] bpf: fix NULL pointer dereference in print_reg_state() Brahmajit Das
2025-09-23 18:52 ` Alexei Starovoitov
2025-09-23 17:10 ` Forwarded: [PATCH] " syzbot
2025-09-23 17:47 ` [PATCH v2] " Brahmajit Das
2025-09-24 7:32 ` Alexei Starovoitov
2025-09-24 9:09 ` Brahmajit Das
2025-09-24 15:40 ` Brahmajit Das
2025-09-24 17:28 ` Alexei Starovoitov
2025-09-24 17:38 ` KaFai Wan
2025-09-24 18:28 ` Brahmajit Das
2025-09-25 15:31 ` KaFai Wan
2025-09-26 1:04 ` Brahmajit Das
2025-09-26 1:56 ` Brahmajit Das
2025-09-26 10:36 ` KaFai Wan
2025-09-30 18:21 ` Brahmajit Das
2025-10-01 5:08 ` KaFai Wan
2025-09-29 18:23 ` [syzbot] [bpf?] general protection fault in print_reg_state syzbot
2025-10-01 9:56 ` [PATCH v3 0/2] bpf: Fix verifier crash on BPF_NEG with pointer register Brahmajit Das
2025-10-01 9:56 ` [PATCH v3 1/2] bpf: Skip scalar adjustment for BPF_NEG if dst is a pointer Brahmajit Das
2025-10-01 16:55 ` Alexei Starovoitov
2025-10-01 18:29 ` Eduard Zingerman
2025-10-01 18:49 ` Brahmajit Das
2025-10-01 18:54 ` Eduard Zingerman
2025-10-01 9:56 ` [PATCH v3 2/2] selftests/bpf: Add test for BPF_NEG alu on CONST_PTR_TO_MAP Brahmajit Das
2025-10-01 18:37 ` Eduard Zingerman
2025-10-01 18:40 ` [PATCH v3 0/2] bpf: Fix verifier crash on BPF_NEG with pointer register Eduard Zingerman
2025-10-01 19:28 ` [PATCH v4 " Brahmajit Das
2025-10-01 19:28 ` [PATCH v4 1/2] bpf: Skip scalar adjustment for BPF_NEG if dst is a pointer Brahmajit Das
2025-10-01 21:10 ` patchwork-bot+netdevbpf
2025-10-01 19:28 ` [PATCH v4 2/2] selftests/bpf: Add test for BPF_NEG alu on CONST_PTR_TO_MAP Brahmajit Das
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