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R. Silva" , Bill Wendling , Justin Stitt , linux-kernel@vger.kernel.org Subject: [PATCH 74/82] ARC: dw2 unwind: Refactor intentional wrap-around test Date: Mon, 22 Jan 2024 16:27:49 -0800 Message-Id: <20240123002814.1396804-74-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=1989; i=keescook@chromium.org; h=from:subject; bh=8xMicWCCIGnY5GKvzZPD3ZX2aaa2K5PDmR+v+tHiKy4=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBlrwgLa43MyLCbPnS7rIKEr6C5f+3w+xjELlHCV wb92b59i9WJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCZa8ICwAKCRCJcvTf3G3A JrpAD/4xhn2HsV5zKKag0M7HS/9i28lHFY4IgZ7Sp/FXWqsjhJpe+6L8PIMzWEBAz92FxtyORdf VL+eitydi1OUF4wQn5MlkJ9CuYUuRkqygF2GNN2Yv1RxYn41vBvNCuYIauc6D5qu0qdxnnP6Md6 84Wz30+PNpfqG+4iMSiroUyKG54Rs5mizS1WG6YfWtx3YbaH1cN9/tF3YP8GRKMwDUUaO0a+eAN KE4rFgsPGobQpzzmomeGjLNzFgA1quKNvV0vj4JNIex/9cb4WYPOVEYFoSmbC7GKjxW+Feoh6sk OvDSN1cF+uHp0J/HNlCu9234++OHS3O99H6uPHVYrJAff5v2Y8xQIZOHQexnwz+XpjOzwRTEaMg AaQwsD98zVWDntX4MOwBtxsAygM2tc6IF7b0qZdHQy3UdlFBRbUiOVa9hOnRJxYLVRxmfZofKAF FszP40YEw5lDzaprhTGytbpNvVCQmqppB3GhHMQrCBA6irAcVze8V7JWHb/QOfsXzW1dfZ+wm6b JqEyk+UA0/YDj29GWvTQ3Eyx1i2tZ6p1xL3sR0USkZszG+zbF2E1aaV1tNGWKi8AysZfjkgMMaP 3hABbeKJFLwRLimh1GaqkDPDGG7vbdgQYbJVljd6TndE+Vys1auQJU6Hdc2dM0CmHHDf3UNBzRC hw1N/vlLdn0dvOw== 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: Vineet Gupta Cc: Luis Chamberlain Cc: "dean.yang_cp" Cc: Song Liu Cc: Yihao Han Cc: linux-snps-arc@lists.infradead.org Signed-off-by: Kees Cook --- arch/arc/kernel/unwind.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arc/kernel/unwind.c b/arch/arc/kernel/unwind.c index 8924fa2a8f29..649b56204580 100644 --- a/arch/arc/kernel/unwind.c +++ b/arch/arc/kernel/unwind.c @@ -1278,7 +1278,7 @@ int arc_unwind(struct unwind_frame_info *frame) if ((state.regs[i].value * state.dataAlign) % sizeof(unsigned long) || addr < startLoc - || addr + sizeof(unsigned long) < addr + || add_would_overflow(addr, sizeof(unsigned long)) || addr + sizeof(unsigned long) > endLoc) return -EIO;