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McKenney" , Shuah Khan , Paul Walmsley , Palmer Dabbelt , Albert Ou , Nathan Chancellor , Nick Desaulniers , Tom Rix Cc: linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-riscv@lists.infradead.org, llvm@lists.linux.dev, =?utf-8?q?Thomas_Wei?= =?utf-8?q?=C3=9Fschuh?= X-Mailer: b4 0.12.2 X-Developer-Signature: v=1; a=ed25519-sha256; t=1684661802; l=1200; i=linux@weissschuh.net; s=20221212; h=from:subject:message-id; bh=LZiWAVpExLBqMgeJqjse39jIjxB9mRmhb4XKNlxTTGk=; b=sO8HDPN/K4znD0QaY3SiD7iD6F2CEv31bBVfF6lPq1g8WZhC0+3FhV31SKjCcBcefvKdmKPMR u0UkQrt0A7sCyn8icIX+chE7SpWFl/tZHzoxx5uxcXyRtJCO35gOzf4 X-Developer-Key: i=linux@weissschuh.net; a=ed25519; pk=KcycQgFPX2wGR5azS7RhpBqedglOZVgRPfdFSPB1LNw= X-Spam-Status: No, score=-2.1 required=5.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,SPF_HELO_NONE,SPF_PASS, T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1766496138057939207?= X-GMAIL-MSGID: =?utf-8?q?1766496138057939207?= The all-zero pattern is one of the more probable out-of-bound writes so add a special case to not accidentally accept it. Also it enables the reliable detection of stack protector initialization during testing. Signed-off-by: Thomas Weißschuh --- tools/include/nolibc/stackprotector.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/tools/include/nolibc/stackprotector.h b/tools/include/nolibc/stackprotector.h index 77e5251c4490..b0156fc077a0 100644 --- a/tools/include/nolibc/stackprotector.h +++ b/tools/include/nolibc/stackprotector.h @@ -45,8 +45,9 @@ __attribute__((weak,no_stack_protector,section(".text.nolibc_stack_chk"))) void __stack_chk_init(void) { my_syscall3(__NR_getrandom, &__stack_chk_guard, sizeof(__stack_chk_guard), 0); - /* a bit more randomness in case getrandom() fails */ - __stack_chk_guard ^= (uintptr_t) &__stack_chk_guard; + /* a bit more randomness in case getrandom() fails, ensure the guard is never 0 */ + if (__stack_chk_guard != (uintptr_t) &__stack_chk_guard) + __stack_chk_guard ^= (uintptr_t) &__stack_chk_guard; } #endif /* defined(NOLIBC_STACKPROTECTOR) */