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R. Silva" , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org Subject: [PATCH 73/82] sh: Refactor intentional wrap-around test Date: Mon, 22 Jan 2024 16:27:48 -0800 Message-Id: <20240123002814.1396804-73-keescook@chromium.org> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240122235208.work.748-kees@kernel.org> References: <20240122235208.work.748-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=1873; i=keescook@chromium.org; h=from:subject; bh=ZK9PQLCXLKqeI6EmNJVF0wuj6cnB4GzhbTbrgojBZ9E=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlrwgLPxEAqie9ltCp6SXpHxJz4a8frf9JpRCdW Ks3k+P95JSJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZa8ICwAKCRCJcvTf3G3A JvckEACcdyYY2SIWpI3UA8mAOkYcOxPIionsaXUa6hl6QfIhatPHcfLoS0jDS13mORx6DesE8QR cEMphGUFZaW309UODp7aj2yCE0TFoSPXkaVTK17BfmoRQIwhtk0f8XfbAE5ingmsTuXMtAnJOsC TuJCmFXEgdPGKvUH3Xb36aFDcfbo+XCAUnEJNX2SZCgGukPkeLLLbjS8PvuLCJtMMEnECnnR1B1 G/OOQHRWemIAHGZHOxhqiqTULKLtQDEb9ah+eWfzVXVhPlSrg2dTXOvPz6UzqYDBuoGKwF5BOIt eXzxRTA/iyaVaOWQawo8BpS7RbJQO6ZgXrwtWcTjjEheh7JWOgHGzCIKRfW2kG45QTP3evtFpIA kOvZdB51R6QuF6t47RBV550QbgsF80t2UmsPYjsToEE0nPBdZ26Iq3l2lQxqDG1fxHv71r2LzjW DH+rai0uNuRUpzJ7IMpon9RPoW2yuFaProOmaiX21mVY9baklpdewo53p9mh/6iRCJ/vuUq/xSi kmUDoE7kbNyXIda7pkfffdCgpbBKQDzjA8F8iTmT9Zrw/O0z3Om2bC/qlgXNnZQLwenVATU5Qrj 1otM6joYjNE87mYWGpZ614abu55pynw/87WeqCPNKZuArSS6+IqDTjPVGcwDtTjK4KqNff/y6iO TlhNUzg3ntPt4Qw== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 In an effort to separate intentional arithmetic wrap-around from unexpected wrap-around, we need to refactor places that depend on this kind of math. One of the most common code patterns of this is: VAR + value < VAR Notably, this is considered "undefined behavior" for signed and pointer types, which the kernel works around by using the -fno-strict-overflow option in the build[1] (which used to just be -fwrapv). Regardless, we want to get the kernel source to the position where we can meaningfully instrument arithmetic wrap-around conditions and catch them when they are unexpected, regardless of whether they are signed[2], unsigned[3], or pointer[4] types. Refactor open-coded wrap-around addition test to use add_would_overflow(). This paves the way to enabling the wrap-around sanitizers in the future. Link: https://git.kernel.org/linus/68df3755e383e6fecf2354a67b08f92f18536594 [1] Link: https://github.com/KSPP/linux/issues/26 [2] Link: https://github.com/KSPP/linux/issues/27 [3] Link: https://github.com/KSPP/linux/issues/344 [4] Cc: Yoshinori Sato Cc: Rich Felker Cc: John Paul Adrian Glaubitz Cc: linux-sh@vger.kernel.org Signed-off-by: Kees Cook Acked-by: John Paul Adrian Glaubitz --- arch/sh/kernel/sys_sh.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/sh/kernel/sys_sh.c b/arch/sh/kernel/sys_sh.c index a5a7b33ed81a..e390caeb8c00 100644 --- a/arch/sh/kernel/sys_sh.c +++ b/arch/sh/kernel/sys_sh.c @@ -66,7 +66,7 @@ asmlinkage int sys_cacheflush(unsigned long addr, unsigned long len, int op) * Verify that the specified address region actually belongs * to this process. */ - if (addr + len < addr) + if (add_would_overflow(addr, len)) return -EFAULT; mmap_read_lock(current->mm);