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[198.145.64.163]) by smtp.gmail.com with ESMTPSA id mm24sm10911696pjb.20.2022.02.03.12.17.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Feb 2022 12:17:58 -0800 (PST) From: Kees Cook To: Alexander Popov Cc: Kees Cook , Peter Zijlstra , Linus Torvalds , Thomas Gleixner , Josh Poimboeuf , Borislav Petkov , linux-kernel@vger.kernel.org, linux-hardening@vger.kernel.org Subject: [PATCH v2] gcc-plugins/stackleak: Use noinstr in favor of notrace Date: Thu, 3 Feb 2022 12:17:54 -0800 Message-Id: <20220203201754.1145358-1-keescook@chromium.org> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2686; h=from:subject; bh=J+F++YLvVFj2qA/cbnqLRM6GuRs8iI1oLzg+aO2Nozs=; b=owEBbQKS/ZANAwAKAYly9N/cbcAmAcsmYgBh/DhxWOpPVb5L6xo6o1Ii29uv7CRbZ520IibHsMqm BeOUkASJAjMEAAEKAB0WIQSlw/aPIp3WD3I+bhOJcvTf3G3AJgUCYfw4cQAKCRCJcvTf3G3AJjQvEA CCZUJKcjDComKd8IeUIlcJkW0zyrAdliB7lSLQHz3ZDhmb8jIcZvT2AYmi9S3xOs6EsLUMGy92BAon k9/DHvMg/pt6pczpaFJhmUuErV3d6Rf2ueeEHJZn8CG0tSeR6lhelUyySAJYcFHUF4uJ156JDjwzPL ahtUwqEK/FprPCHiFSaU2XN2nBpZIf47wZpKS4r+j5XKBeUdt3meGFGohZO8FOeW7oBKhj9iTYqMdx JTJ0TjBnzIgYJ9UQ0eIWVmEsKkjBAZ/lipeSPpiOGGoJiEBbY4ljycjo7/Z+fhNjCQs/m01oZ+++1R TI7RiHBOHSkmLoofChLzr1qTJmE/piIL7i/RexiqH/913CSf8+Muu2G0qFu32Efvb3Lw2gySRXPuXG gKV0EmYfqUgJ+tqReLEtpJh+K0K8oQtuxnfd3twFBjK7YdDh90iAvSl3lAuMbFPFTstXqt8kmwGhF0 qkggauQsgsBB+opMKEE7ktHeSmBTt77UgtXATyRu6nAdS0ST6+n++ZexFAtRLmfFJ2+7MN4txNKe6n 8YjI4oXr5ltiXtx/doxMGKi9GcimxzeZdLzGRlgaD593AhzNevdHUEQUcI4gst4kkDx7NryHhl9gpU 6JpqFGBtAKysphvt22Xy4UK71NBhj28E03DGmruTjLnqBgVJW2OOIZFVH5PQ== X-Developer-Key: i=keescook@chromium.org; a=openpgp; fpr=A5C3F68F229DD60F723E6E138972F4DFDC6DC026 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-hardening@vger.kernel.org While the stackleak plugin was already using notrace, objtool is now a bit more picky. Update the notrace uses to noinstr. Silences the following objtool warnings when building with: CONFIG_DEBUG_ENTRY=y CONFIG_STACK_VALIDATION=y CONFIG_VMLINUX_VALIDATION=y CONFIG_GCC_PLUGIN_STACKLEAK=y vmlinux.o: warning: objtool: do_syscall_64()+0x9: call to stackleak_track_stack() leaves .noinstr.text section vmlinux.o: warning: objtool: do_int80_syscall_32()+0x9: call to stackleak_track_stack() leaves .noinstr.text section vmlinux.o: warning: objtool: exc_general_protection()+0x22: call to stackleak_track_stack() leaves .noinstr.text section vmlinux.o: warning: objtool: fixup_bad_iret()+0x20: call to stackleak_track_stack() leaves .noinstr.text section vmlinux.o: warning: objtool: do_machine_check()+0x27: call to stackleak_track_stack() leaves .noinstr.text section vmlinux.o: warning: objtool: .text+0x5346e: call to stackleak_erase() leaves .noinstr.text section vmlinux.o: warning: objtool: .entry.text+0x143: call to stackleak_erase() leaves .noinstr.text section vmlinux.o: warning: objtool: .entry.text+0x10eb: call to stackleak_erase() leaves .noinstr.text section vmlinux.o: warning: objtool: .entry.text+0x17f9: call to stackleak_erase() leaves .noinstr.text section Note that the plugin's addition of calls to stackleak_track_stack() from noinstr functions is expected to be safe, as it isn't runtime instrumentation and is self-contained. Cc: Alexander Popov Suggested-by: Peter Zijlstra Signed-off-by: Kees Cook --- kernel/stackleak.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) diff --git a/kernel/stackleak.c b/kernel/stackleak.c index 66b8af394e58..ddb5a7f48d69 100644 --- a/kernel/stackleak.c +++ b/kernel/stackleak.c @@ -70,7 +70,7 @@ late_initcall(stackleak_sysctls_init); #define skip_erasing() false #endif /* CONFIG_STACKLEAK_RUNTIME_DISABLE */ -asmlinkage void notrace stackleak_erase(void) +asmlinkage void noinstr stackleak_erase(void) { /* It would be nice not to have 'kstack_ptr' and 'boundary' on stack */ unsigned long kstack_ptr = current->lowest_stack; @@ -124,9 +124,8 @@ asmlinkage void notrace stackleak_erase(void) /* Reset the 'lowest_stack' value for the next syscall */ current->lowest_stack = current_top_of_stack() - THREAD_SIZE/64; } -NOKPROBE_SYMBOL(stackleak_erase); -void __used __no_caller_saved_registers notrace stackleak_track_stack(void) +void __used __no_caller_saved_registers noinstr stackleak_track_stack(void) { unsigned long sp = current_stack_pointer; -- 2.30.2