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Fri, 13 Nov 2026 15:50:47 -0800 (PST) Received: from localhost ([153.61.198.241]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-3b197c6c9c5sm11507001a91.1.2026.11.13.15.50.45 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 13 Nov 2026 15:50:46 -0800 (PST) Content-Type: text/plain; charset=UTF-8 Date: Fri, 13 Nov 2026 23:50:45 +0000 Message-Id: Subject: Re: [PATCH bpf] bpf: mask speculative out-of-bounds skb helper loads From: "Alexei Starovoitov" To: , =?utf-8?q?Dani=C3=ABl_Trujillo_via_B4_Relay?= , "Daniel Borkmann" , "Andrii Nakryiko" , "Eduard Zingerman" , "Kumar Kartikeya Dwivedi" , "Martin KaFai Lau" , "Song Liu" , "Yonghong Song" , "Jiri Olsa" , "Emil Tsalapatis" , "Ihor Solodrai" , "John Fastabend" , "Stanislav Fomichev" , "David S. Miller" , "Eric Dumazet" , "Jakub Kicinski" , "Paolo Abeni" , "Simon Horman" Cc: , , In-Reply-To: <20261113-cbpf-ind-nospec-v1-bpf-v1-1-764ac4c14573@nvidia.com> References: <20261113-cbpf-ind-nospec-v1-bpf-v1-1-764ac4c14573@nvidia.com> Content-Transfer-Encoding: 8bit X-Mailing-List: bpf@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 On Fri, Nov 13, 2026 at 12:15 PM Daniël Trujillo via B4 Relay 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