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Wed, 23 Sep 2026 22:55:10 -0700 (PDT) Content-Type: text/plain; charset=UTF-8 Date: Thu, 24 Sep 2026 05:55:09 +0000 Message-Id: Cc: "Andrii Nakryiko" , "Daniel Borkmann" , "Eduard Zingerman" , "Emil Tsalapatis" , , Subject: Re: [PATCH bpf-next v1 1/3] bpf: Check fastcall contract for helper and kfunc stack buffers From: "Alexei Starovoitov" To: "Kumar Kartikeya Dwivedi" , In-Reply-To: <20260923084201.2437625-2-memxor@gmail.com> References: <20260923084201.2437625-1-memxor@gmail.com> <20260923084201.2437625-2-memxor@gmail.com> X-Mailer: mkdraft (claude review draft; edit before sending) Content-Transfer-Encoding: 8bit Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 On Wed, Sep 23, 2026 at 10:41 AM Kumar Kartikeya Dwivedi wrote: > + /* > + * Helpers and kfuncs can access stack slots without going through the > + * regular stack read/write paths, including when raw mode is disabled. > + */ > + if (access_size) > + check_fastcall_stack_contract(env, state, env->insn_idx, min_off); can we do it once in check_stack_access_within_bounds() ? Both check_mem_access() and check_stack_range_initialized() call it first, and it already has the frame that owns the slot and min_off. Then the other four check_fastcall_stack_contract() calls can go and patch 2 is not needed.