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Subject[PATCH 5.3 139/344] s390/kasan: provide uninstrumented __strlen
From: Vasily Gorbik <>

[ Upstream commit f45f7b5bdaa4828ce871cf03f7c01599a0de57a5 ]

s390 kasan code uses sclp_early_printk to report initialization
failures. The code doing that should not be instrumented, because kasan
shadow memory has not been set up yet. Even though sclp_early_core.c is
compiled with instrumentation disabled it uses strlen function, which
is instrumented and would produce shadow memory access if used. To
avoid that, introduce uninstrumented __strlen function to be used

Before commit 7e0d92f00246 ("s390/kasan: improve string/memory functions
checks") few string functions (including strlen) were escaping kasan
instrumentation due to usage of platform specific versions which are
implemented in inline assembly.

Fixes: 7e0d92f00246 ("s390/kasan: improve string/memory functions checks")
Acked-by: Ilya Leoshkevich <>
Signed-off-by: Vasily Gorbik <>
Signed-off-by: Sasha Levin <>
arch/s390/include/asm/string.h | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/arch/s390/include/asm/string.h b/arch/s390/include/asm/string.h
index 70d87db54e627..4c0690fc5167e 100644
--- a/arch/s390/include/asm/string.h
+++ b/arch/s390/include/asm/string.h
@@ -71,11 +71,16 @@ extern void *__memmove(void *dest, const void *src, size_t n);
#define memcpy(dst, src, len) __memcpy(dst, src, len)
#define memmove(dst, src, len) __memmove(dst, src, len)
#define memset(s, c, n) __memset(s, c, n)
+#define strlen(s) __strlen(s)
+#define __no_sanitize_prefix_strfunc(x) __##x

#ifndef __NO_FORTIFY
#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */

+#define __no_sanitize_prefix_strfunc(x) x
#endif /* defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__) */

void *__memset16(uint16_t *s, uint16_t v, size_t count);
@@ -163,8 +168,8 @@ static inline char *strcpy(char *dst, const char *src)

-static inline size_t strlen(const char *s)
+#if defined(__HAVE_ARCH_STRLEN) || (defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__))
+static inline size_t __no_sanitize_prefix_strfunc(strlen)(const char *s)
register unsigned long r0 asm("0") = 0;
const char *tmp = s;

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