linux-kernel - [PATCH 1/2] arm64: kasan: do not instrument stacktrace.c

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <697e015e22ea78b021c2546f390ad5d773f3af86.1653177005.git.andreyknvl@google.com>
Date:   Sun, 22 May 2022 01:50:58 +0200
From:   andrey.konovalov@...ux.dev
To:     Mark Rutland <mark.rutland@....com>
Cc:     Andrey Konovalov <andreyknvl@...il.com>,
        Marco Elver <elver@...gle.com>,
        Alexander Potapenko <glider@...gle.com>,
        Dmitry Vyukov <dvyukov@...gle.com>,
        Andrey Ryabinin <ryabinin.a.a@...il.com>,
        kasan-dev@...glegroups.com,
        Catalin Marinas <catalin.marinas@....com>,
        Vincenzo Frascino <vincenzo.frascino@....com>,
        Will Deacon <will@...nel.org>,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        Andrey Konovalov <andreyknvl@...gle.com>
Subject: [PATCH 1/2] arm64: kasan: do not instrument stacktrace.c

From: Andrey Konovalov <andreyknvl@...gle.com>

Disable KASAN instrumentation of arch/arm64/kernel/stacktrace.c.

This speeds up Generic KASAN by 5-20%.

As a side-effect, KASAN is now unable to detect bugs in the stack trace
collection code. This is taken as an acceptable downside.

Also replace READ_ONCE_NOCHECK() with READ_ONCE() in stacktrace.c.
As the file is now not instrumented, there is no need to use the
NOCHECK version of READ_ONCE().

Suggested-by: Mark Rutland <mark.rutland@....com>
Signed-off-by: Andrey Konovalov <andreyknvl@...gle.com>
---
 arch/arm64/kernel/Makefile     | 3 +++
 arch/arm64/kernel/stacktrace.c | 4 ++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/arch/arm64/kernel/Makefile b/arch/arm64/kernel/Makefile
index fa7981d0d917..da8cf6905c76 100644
--- a/arch/arm64/kernel/Makefile
+++ b/arch/arm64/kernel/Makefile
@@ -14,6 +14,9 @@ CFLAGS_REMOVE_return_address.o = $(CC_FLAGS_FTRACE)
 CFLAGS_REMOVE_syscall.o	 = -fstack-protector -fstack-protector-strong
 CFLAGS_syscall.o	+= -fno-stack-protector
 
+# Do not instrument to improve performance.
+KASAN_SANITIZE_stacktrace.o := n
+
 # It's not safe to invoke KCOV when portions of the kernel environment aren't
 # available or are out-of-sync with HW state. Since `noinstr` doesn't always
 # inhibit KCOV instrumentation, disable it for the entire compilation unit.
diff --git a/arch/arm64/kernel/stacktrace.c b/arch/arm64/kernel/stacktrace.c
index e4103e085681..33e96ae4b15f 100644
--- a/arch/arm64/kernel/stacktrace.c
+++ b/arch/arm64/kernel/stacktrace.c
@@ -110,8 +110,8 @@ static int notrace unwind_frame(struct task_struct *tsk,
 	 * Record this frame record's values and location. The prev_fp and
 	 * prev_type are only meaningful to the next unwind_frame() invocation.
 	 */
-	frame->fp = READ_ONCE_NOCHECK(*(unsigned long *)(fp));
-	frame->pc = READ_ONCE_NOCHECK(*(unsigned long *)(fp + 8));
+	frame->fp = READ_ONCE(*(unsigned long *)(fp));
+	frame->pc = READ_ONCE(*(unsigned long *)(fp + 8));
 	frame->prev_fp = fp;
 	frame->prev_type = info.type;
 
-- 
2.25.1