From: "Alexei Starovoitov" <alexei.starovoitov@gmail.com>
To: datrujillo@nvidia.com,
"Daniël Trujillo via B4 Relay"
<devnull+datrujillo.nvidia.com@kernel.org>,
"Daniel Borkmann" <daniel@iogearbox.net>,
"Andrii Nakryiko" <andrii@kernel.org>,
"Eduard Zingerman" <eddyz87@gmail.com>,
"Kumar Kartikeya Dwivedi" <memxor@gmail.com>,
"Martin KaFai Lau" <martin.lau@linux.dev>,
"Song Liu" <song@kernel.org>,
"Yonghong Song" <yonghong.song@linux.dev>,
"Jiri Olsa" <jolsa@kernel.org>,
"Emil Tsalapatis" <emil@etsalapatis.com>,
"Ihor Solodrai" <ihor.solodrai@linux.dev>,
"John Fastabend" <john.fastabend@gmail.com>,
"Stanislav Fomichev" <sdf@fomichev.me>,
"David S. Miller" <davem@davemloft.net>,
"Eric Dumazet" <edumazet@kernel.org>,
"Jakub Kicinski" <kuba@kernel.org>,
"Paolo Abeni" <pabeni@redhat.com>,
"Simon Horman" <horms@kernel.org>
Cc: <bpf@vger.kernel.org>, <netdev@vger.kernel.org>,
<linux-kernel@vger.kernel.org>
Subject: Re: [PATCH bpf] bpf: mask speculative out-of-bounds skb helper loads
Date: Fri, 13 Nov 2026 23:50:45 +0000 [thread overview]
Message-ID: <DMUHIJ5FC8EA.2XFM7TJ6AH0YB@gmail.com> (raw)
In-Reply-To: <20261113-cbpf-ind-nospec-v1-bpf-v1-1-764ac4c14573@nvidia.com>
On Fri, Nov 13, 2026 at 12:15 PM Daniël Trujillo via B4 Relay <devnull+datrujillo.nvidia.com@kernel.org> wrote:
> Mask the load address when the converted offset falls outside the
> permitted range. This removed the leakage in the described setup.
> Derive the lower bound from the network and MAC header
> positions. An out-of-bounds transient offset dereferences NULL instead
> of a potential secret.
I suspect you don't have a reproducer and it's all theoretical.
Because if you had one you would have seen that your patch does nothing.
convert_bpf_ld_abs() inlines the LD_ABS fast
path with its own bounds check.
wont-fix.
pw-bot: cr
prev parent reply other threads:[~2026-11-13 23:50 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-11-13 20:15 [PATCH bpf] bpf: mask speculative out-of-bounds skb helper loads Daniël Trujillo via B4 Relay
2026-11-13 20:46 ` bot+bpf-ci
2026-11-13 22:10 ` Daniel Trujillo
2026-11-13 23:50 ` Alexei Starovoitov [this message]
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