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[82.69.66.36]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-38dbde0fe37sm2561146f8f.69.2025.02.06.11.56.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 06 Feb 2025 11:56:59 -0800 (PST) Date: Thu, 6 Feb 2025 19:56:58 +0000 From: David Laight To: Kees Cook Cc: Suren Baghdasaryan , Kent Overstreet , Andy Shevchenko , Luc Van Oostenryck , Nathan Chancellor , Nick Desaulniers , Bill Wendling , Justin Stitt , Philipp Reisner , Miguel Ojeda , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org, llvm@lists.linux.dev Subject: Re: [PATCH 2/3] compiler.h: Introduce __must_be_char_array() Message-ID: <20250206195658.79231973@pumpkin> In-Reply-To: <20250206181133.3450635-2-kees@kernel.org> References: <20250206175216.work.225-kees@kernel.org> <20250206181133.3450635-2-kees@kernel.org> 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 Thu, 6 Feb 2025 10:11:29 -0800 Kees Cook wrote: > In preparation for adding stricter type checking to the str/mem*() > helpers, provide a way to check that a variable is a character array > via __must_be_char_array(). > ... > +#define __is_char_array(a) (__is_array(a) && sizeof((a)[0]) == 1) > +#define __must_be_char_array(a) __BUILD_BUG_ON_ZERO_MSG(!__is_char_array(a), \ > + "must be byte array") If you are only checking the size, perhaps __is_byte_array() would be a better name. (You've even used 'byte' in the error message.) David