From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 540B7C43217 for ; Mon, 28 Mar 2022 11:23:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240895AbiC1LZO (ORCPT ); Mon, 28 Mar 2022 07:25:14 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57442 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241215AbiC1LXX (ORCPT ); Mon, 28 Mar 2022 07:23:23 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7D37E5881D; Mon, 28 Mar 2022 04:20:25 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 7A52E61193; Mon, 28 Mar 2022 11:20:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 38D29C340ED; Mon, 28 Mar 2022 11:20:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1648466418; bh=hOasPOHGeymPIR9CFGjXih8tpW9A6b/MeZtf9fDUetE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=juJxDTPo4QnUZ+t+HSCayFwd5s5Rk4A++ocMKPMMQu9RXg1DrmZ2CGiTu2OWYayX/ iq0Nn0giHyTezrGB81JzVxifDHIaZoS80O2Ho6kgMnLcPeYDsU377BKqY1xzk3jmpP Ed2DN3uF58fIaY7RYPPXXTDqm39WKlc0tnGlSHLwAiewrmUrzS6eWhomhN+SVHuw/G xXNAvIHFPNdyGq1Lh8y1+s6J3YT+m7meZ6+4iEkPiXOQ+dY965J6FnN9It6Gg4NTXc lE12YU/Q657j/dOUobioTNXn2jaLnU+Hkq/K7xgtCIwTX1NP5kfUT3oD2yveTXeBAJ a029hl5gEnxQA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Kees Cook , Alexander Popov , Sasha Levin , linux-hardening@vger.kernel.org Subject: [PATCH AUTOSEL 5.16 04/35] gcc-plugins/stackleak: Exactly match strings instead of prefixes Date: Mon, 28 Mar 2022 07:19:40 -0400 Message-Id: <20220328112011.1555169-4-sashal@kernel.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20220328112011.1555169-1-sashal@kernel.org> References: <20220328112011.1555169-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Kees Cook [ Upstream commit 27e9faf415dbf94af19b9c827842435edbc1fbbc ] Since STRING_CST may not be NUL terminated, strncmp() was used for check for equality. However, this may lead to mismatches for longer section names where the start matches the tested-for string. Test for exact equality by checking for the presences of NUL termination. Cc: Alexander Popov Signed-off-by: Kees Cook Signed-off-by: Sasha Levin --- scripts/gcc-plugins/stackleak_plugin.c | 25 +++++++++++++++++++++---- 1 file changed, 21 insertions(+), 4 deletions(-) diff --git a/scripts/gcc-plugins/stackleak_plugin.c b/scripts/gcc-plugins/stackleak_plugin.c index e9db7dcb3e5f..b04aa8e91a41 100644 --- a/scripts/gcc-plugins/stackleak_plugin.c +++ b/scripts/gcc-plugins/stackleak_plugin.c @@ -429,6 +429,23 @@ static unsigned int stackleak_cleanup_execute(void) return 0; } +/* + * STRING_CST may or may not be NUL terminated: + * https://gcc.gnu.org/onlinedocs/gccint/Constant-expressions.html + */ +static inline bool string_equal(tree node, const char *string, int length) +{ + if (TREE_STRING_LENGTH(node) < length) + return false; + if (TREE_STRING_LENGTH(node) > length + 1) + return false; + if (TREE_STRING_LENGTH(node) == length + 1 && + TREE_STRING_POINTER(node)[length] != '\0') + return false; + return !memcmp(TREE_STRING_POINTER(node), string, length); +} +#define STRING_EQUAL(node, str) string_equal(node, str, strlen(str)) + static bool stackleak_gate(void) { tree section; @@ -438,13 +455,13 @@ static bool stackleak_gate(void) if (section && TREE_VALUE(section)) { section = TREE_VALUE(TREE_VALUE(section)); - if (!strncmp(TREE_STRING_POINTER(section), ".init.text", 10)) + if (STRING_EQUAL(section, ".init.text")) return false; - if (!strncmp(TREE_STRING_POINTER(section), ".devinit.text", 13)) + if (STRING_EQUAL(section, ".devinit.text")) return false; - if (!strncmp(TREE_STRING_POINTER(section), ".cpuinit.text", 13)) + if (STRING_EQUAL(section, ".cpuinit.text")) return false; - if (!strncmp(TREE_STRING_POINTER(section), ".meminit.text", 13)) + if (STRING_EQUAL(section, ".meminit.text")) return false; } -- 2.34.1