From patchwork Thu Feb 6 18:11:30 2025 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Kees Cook X-Patchwork-Id: 13963416 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 36E37199385; Thu, 6 Feb 2025 18:11:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738865494; cv=none; b=f6CpW+kRsjh5B/0g31EIbPNmdt7KICwDi129Q9UCYMpuEvAQFZAPMi+P7CvNTpDh7coOqJJGMCkkxl3q+UU31Dfm+jz/e5iEZ6yby+xmYP26S9UBsPlMnN8KpipnGaLw1vYwdvZBfc1Rg+hsSoF6CNuUbINCksGVXzmSMWrQRo4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1738865494; c=relaxed/simple; bh=91NW6YxsPuJbVe3TMPcFmsEh91512TgV/JV4nGsNPQE=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=b/LCcoibXkxk9ozMDeFuAh+kBrTlwJduJ/arQ/p5QrHXDlsZOub3AbGuzf1Hs85QNAazp591qXshXhHzkWB2ngUKj0w7Q7ezsrSpRyGuKxaLjij/zubT1837h+1lketRIXXV6iu7WI1FbMjympOOLF9fFdztW5wHoSntENDx4NY= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=hDZXDJqd; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="hDZXDJqd" Received: by smtp.kernel.org (Postfix) with ESMTPSA id ADC5CC4CEDF; Thu, 6 Feb 2025 18:11:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1738865493; bh=91NW6YxsPuJbVe3TMPcFmsEh91512TgV/JV4nGsNPQE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hDZXDJqdsiDEJH8nm7vStlfBSE3tLcw1hTN9zCDU2AEJ3daWpqpW6QQghoNoTXpOX yllVXQ8dOIgBNnghe4QIyuxkLOMKJD3m1blrO6J9PustNQfsN8uoTvOpm7AIV8aB/4 le7CAM7Po49M0BhZwdvOKqAI9vm2igVYZIp3GhL2FVwZZofYu0k2dCdYVEXri5zIk8 azL90kGmmxKh+CBiMx8722jlCFT3HAVoL+itkrWIZRyh47Y45enPm0uJ+t1hfUk8VI XqIHYfG7LzajYpHkjoH3MIdmrza2lIQcitMsuIVRW2Y6fcAugnNdCGNerJFxcWZ5kL MJ3IY6jO/OWPg== From: Kees Cook To: Suren Baghdasaryan Cc: Kees Cook , kernel test robot , Kent Overstreet , nathan@kernel.org, Andy Shevchenko , linux-hardening@vger.kernel.org, Luc Van Oostenryck , Nick Desaulniers , Bill Wendling , Justin Stitt , Philipp Reisner , Miguel Ojeda , linux-kernel@vger.kernel.org, llvm@lists.linux.dev Subject: [PATCH 3/3] string.h: Use ARRAY_SIZE() for memtostr*()/strtomem*() Date: Thu, 6 Feb 2025 10:11:30 -0800 Message-Id: <20250206181133.3450635-3-kees@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20250206175216.work.225-kees@kernel.org> References: <20250206175216.work.225-kees@kernel.org> Precedence: bulk X-Mailing-List: linux-hardening@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3185; i=kees@kernel.org; h=from:subject; bh=91NW6YxsPuJbVe3TMPcFmsEh91512TgV/JV4nGsNPQE=; b=owGbwMvMwCVmps19z/KJym7G02pJDOlLfge+aZ34u+olw66rrsfm/uO9Xzn7NduNMEE+sT2KW QwnPz6u6ChlYRDjYpAVU2QJsnOPc/F42x7uPlcRZg4rE8gQBi5OAZjInScM/6OPFn86LvD4iOxz C9aqBccCbsyo+NJZGfloi7B6hVp1YgojwwWR/JO3r/fkM97+N3PunTWZS8vOml75sfhMYWDA8Vl KR9gA X-Developer-Key: i=kees@kernel.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 The destination argument of memtostr*() and strtomem*() must be a fixed-size char array at compile time, so there is no need to use __builtin_object_size() (which is useful for when an argument is either a pointer or unknown). Instead use ARRAY_SIZE(), which has the benefit of working around a bug in Clang (fixed[1] in 15+) that got __builtin_object_size() wrong sometimes. Reported-by: kernel test robot Closes: https://lore.kernel.org/oe-kbuild-all/202501310832.kiAeOt2z-lkp@intel.com/ Suggested-by: Kent Overstreet Link: https://github.com/llvm/llvm-project/commit/d8e0a6d5e9dd2311641f9a8a5d2bf90829951ddc [1] Signed-off-by: Kees Cook --- Cc: Suren Baghdasaryan Cc: nathan@kernel.org Cc: Andy Shevchenko Cc: linux-hardening@vger.kernel.org --- include/linux/string.h | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/include/linux/string.h b/include/linux/string.h index 493ac4862c77..01ac26be274d 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -411,7 +411,8 @@ void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count, * must be discoverable by the compiler. */ #define strtomem_pad(dest, src, pad) do { \ - const size_t _dest_len = __builtin_object_size(dest, 1); \ + const size_t _dest_len = __must_be_char_array(dest) + \ + ARRAY_SIZE(dest); \ const size_t _src_len = __builtin_object_size(src, 1); \ \ BUILD_BUG_ON(!__builtin_constant_p(_dest_len) || \ @@ -434,7 +435,8 @@ void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count, * must be discoverable by the compiler. */ #define strtomem(dest, src) do { \ - const size_t _dest_len = __builtin_object_size(dest, 1); \ + const size_t _dest_len = __must_be_char_array(dest) + \ + ARRAY_SIZE(dest); \ const size_t _src_len = __builtin_object_size(src, 1); \ \ BUILD_BUG_ON(!__builtin_constant_p(_dest_len) || \ @@ -453,7 +455,8 @@ void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count, * Note that sizes of @dest and @src must be known at compile-time. */ #define memtostr(dest, src) do { \ - const size_t _dest_len = __builtin_object_size(dest, 1); \ + const size_t _dest_len = __must_be_char_array(dest) + \ + ARRAY_SIZE(dest); \ const size_t _src_len = __builtin_object_size(src, 1); \ const size_t _src_chars = strnlen(src, _src_len); \ const size_t _copy_len = min(_dest_len - 1, _src_chars); \ @@ -478,7 +481,8 @@ void memcpy_and_pad(void *dest, size_t dest_len, const void *src, size_t count, * Note that sizes of @dest and @src must be known at compile-time. */ #define memtostr_pad(dest, src) do { \ - const size_t _dest_len = __builtin_object_size(dest, 1); \ + const size_t _dest_len = __must_be_char_array(dest) + \ + ARRAY_SIZE(dest); \ const size_t _src_len = __builtin_object_size(src, 1); \ const size_t _src_chars = strnlen(src, _src_len); \ const size_t _copy_len = min(_dest_len - 1, _src_chars); \