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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id g27sm4893301pgl.19.2021.07.27.13.59.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 27 Jul 2021 13:59:14 -0700 (PDT) From: Kees Cook To: linux-hardening@vger.kernel.org Cc: Kees Cook , "Gustavo A. R. Silva" , Keith Packard , Greg Kroah-Hartman , Andrew Morton , linux-kernel@vger.kernel.org, linux-wireless@vger.kernel.org, netdev@vger.kernel.org, dri-devel@lists.freedesktop.org, linux-staging@lists.linux.dev, linux-block@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com Subject: [PATCH 64/64] fortify: Add run-time WARN for cross-field memcpy() Date: Tue, 27 Jul 2021 13:58:55 -0700 Message-Id: <20210727205855.411487-65-keescook@chromium.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210727205855.411487-1-keescook@chromium.org> References: <20210727205855.411487-1-keescook@chromium.org> MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=1942; h=from:subject; bh=RTdC1l2OZqdjmeHWbAdwbLJoQzG6khjndsQEFnTv5CQ=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBhAHOOoYe9sIhYxHQvPTRJ442xiTpScfryHfKvIe1i sHyzRDqJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYQBzjgAKCRCJcvTf3G3AJgaOEA ChcfQRhtSTlAFifX9KeThgQ0Uq0d8HgqX9d7L7di9/gmd2+q9a2jOeVLC8gckPM5zLCPjGAPeADcAJ d66hhTLJ1w+E4pD+VvWPPeopnlvv/UVfWd8PB4LJbpoWEceJ6eDTiiC/iLcY/ccmaowSsyM+RD0OP5 pMnkTErmHRoT4p4KW6sBF/D5BjOB39tfSy91Re1raHesEqaFybA9fcJflSdn9W1aI0bHciireUFofB T7rpT4s4qFia+UxE36sxzshuQHwig6S/H7514YsynGyxfM2Qklu8gbfDJ6LAQkHClc0bfyTIiXESyg ywDP93+de3A/S6fGfgl93xa940kRjzrhL1qnzlP0zaVOVbpcgLzsYJ545IJ+TmM8HpJfojPa8GKSuj R4VLih6/XrTEQA2B5d0z/qwYFEm2tk1ALTz5bfkiQLeNBQmj07WzORr0H4yRF3LHyo1EMp06zJeCss ob/ijvKIueEYm1x2q9NTIgloeNO+GTCHYSFzMjtXiJQtqMTwWCPDd7OHie3E3Zdy5kLslb0XwSb4bI 13oeoYOHrWStAAAcuZNIxS1XS1W9LtGkezYc7wGb1YsgX/cpuksW4RJ70bOOYlCUI7ORAmfo/O5xvj 2M/YGfM4cY13yTZbLkY8Kekpx9XUxEtviQZlLWMI0ntWBHVrpbS8XpEjS9xA== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org This enables the run-time checking of dynamic memcpy() and memmove() lengths, issuing a WARN when a write would exceed the size of the target field. Signed-off-by: Kees Cook --- include/linux/fortify-string.h | 18 +++++++++++++++--- 1 file changed, 15 insertions(+), 3 deletions(-) diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h index 4afd42079d3b..0d0acd959ba0 100644 --- a/include/linux/fortify-string.h +++ b/include/linux/fortify-string.h @@ -260,7 +260,7 @@ __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size, * V = vulnerable to run-time overflow * */ -__FORTIFY_INLINE void fortify_memcpy_chk(__kernel_size_t size, +__FORTIFY_INLINE bool fortify_memcpy_chk(__kernel_size_t size, const size_t p_size, const size_t q_size, const size_t p_size_field, @@ -309,13 +309,25 @@ __FORTIFY_INLINE void fortify_memcpy_chk(__kernel_size_t size, if ((p_size != (size_t)(-1) && p_size < size) || (q_size != (size_t)(-1) && q_size < size)) fortify_panic(func); + + /* + * Warn when writing beyond destination field size. Since + * flexible-arrays are considered 0 bytes, we must ignore 0 sizes + * at runtime for now. + */ + if (p_size_field && p_size != p_size_field && p_size_field < size) + return true; + + return false; } #define __fortify_memcpy_chk(p, q, size, p_size, q_size, \ p_size_field, q_size_field, op) ({ \ size_t __fortify_size = (size_t)(size); \ - fortify_memcpy_chk(__fortify_size, p_size, q_size, \ - p_size_field, q_size_field, #op); \ + WARN_ONCE(fortify_memcpy_chk(__fortify_size, p_size, q_size, \ + p_size_field, q_size_field, #op), \ + #op ": detected field-spanning write (size %zu) of single field (size %zu)\n", \ + __fortify_size, p_size_field); \ __underlying_##op(p, q, __fortify_size); \ })