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[174.21.150.71]) by smtp.gmail.com with ESMTPSA id me3sm164189pjb.32.2021.02.09.16.02.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 09 Feb 2021 16:02:32 -0800 (PST) From: Richard Henderson To: qemu-devel@nongnu.org Subject: [PATCH v6 06/31] linux-user: Check for overflow in access_ok Date: Tue, 9 Feb 2021 16:01:58 -0800 Message-Id: <20210210000223.884088-7-richard.henderson@linaro.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20210210000223.884088-1-richard.henderson@linaro.org> References: <20210210000223.884088-1-richard.henderson@linaro.org> MIME-Version: 1.0 Received-SPF: pass client-ip=2607:f8b0:4864:20::102e; envelope-from=richard.henderson@linaro.org; helo=mail-pj1-x102e.google.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Verify that addr + size - 1 does not wrap around. Reviewed-by: Peter Maydell Signed-off-by: Richard Henderson --- linux-user/qemu.h | 17 ++++++++++++----- 1 file changed, 12 insertions(+), 5 deletions(-) diff --git a/linux-user/qemu.h b/linux-user/qemu.h index 17aa992165..441ba6a78b 100644 --- a/linux-user/qemu.h +++ b/linux-user/qemu.h @@ -491,12 +491,19 @@ extern unsigned long guest_stack_size; #define VERIFY_READ 0 #define VERIFY_WRITE 1 /* implies read access */ -static inline int access_ok(int type, abi_ulong addr, abi_ulong size) +static inline bool access_ok(int type, abi_ulong addr, abi_ulong size) { - return guest_addr_valid(addr) && - (size == 0 || guest_addr_valid(addr + size - 1)) && - page_check_range((target_ulong)addr, size, - (type == VERIFY_READ) ? PAGE_READ : (PAGE_READ | PAGE_WRITE)) == 0; + if (!guest_addr_valid(addr)) { + return false; + } + if (size != 0 && + (addr + size - 1 < addr || + !guest_addr_valid(addr + size - 1))) { + return false; + } + return page_check_range((target_ulong)addr, size, + (type == VERIFY_READ) ? PAGE_READ : + (PAGE_READ | PAGE_WRITE)) == 0; } /* NOTE __get_user and __put_user use host pointers and don't check access.