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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4792b02e842sm13726135e9.1.2025.12.03.03.02.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 03 Dec 2025 03:02:28 -0800 (PST) Date: Wed, 3 Dec 2025 11:02:26 +0000 From: David Laight To: Josh Poimboeuf Cc: Ingo Molnar , x86@kernel.org, linux-kernel@vger.kernel.org, Nathan Chancellor , Peter Zijlstra , Alexandre Chartre Subject: Re: [PATCH] objtool: Fix stack overflow in validate_branch() Message-ID: <20251203110226.4ae00f1f@pumpkin> In-Reply-To: References: <21bb161c23ca0d8c942a960505c0d327ca2dc7dc.1764691895.git.jpoimboe@kernel.org> <20251202220540.5849bdc6@pumpkin> X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; arm-unknown-linux-gnueabihf) Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Tue, 2 Dec 2025 15:01:17 -0800 Josh Poimboeuf wrote: ... > + while (fgets(line, sizeof(line), fp)) { > + if (strstr(line, "[stack]")) { > + if (sscanf(line, "%lx-%lx", &stack_start, &stack_end) != 2) { > + ERROR_GLIBC("sscanf"); > + ret = -1; > + goto done; > + } > + stack_limit = stack_end - rlim.rlim_cur; > + goto done; That assumes 'stack grows down'. Someone will copy the code onto a 'backwards stack' system one day. (I can't remember which ones they are.) David