Re: [RFC PATCH v2 3/3] kasan: add interceptors for all string functions

[Christophe Leroy <christophe.leroy@c-s.fr>]

Hi Dmitry, Andrey and others,

Do you have any comments to this series ?

I'd like to know if this approach is ok or if it is better to keep doing 
as in https://patchwork.ozlabs.org/patch/1055788/

Thanks
Christophe

Le 28/03/2019 à 16:00, Christophe Leroy a écrit :
> In the same spirit as commit 393f203f5fd5 ("x86_64: kasan: add
> interceptors for memset/memmove/memcpy functions"), this patch
> adds interceptors for string manipulation functions so that we
> can compile lib/string.o without kasan support hence allow the
> string functions to also be used from places where kasan has
> to be disabled.
> 
> Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> ---
>   v2: Fixed a few checkpatch stuff and added missing EXPORT_SYMBOL() and missing #undefs
> 
>   include/linux/string.h |  79 ++++++++++
>   lib/Makefile           |   2 +
>   lib/string.c           |   8 +
>   mm/kasan/string.c      | 394 +++++++++++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 483 insertions(+)
> 
> diff --git a/include/linux/string.h b/include/linux/string.h
> index 7927b875f80c..3d2aff2ed402 100644
> --- a/include/linux/string.h
> +++ b/include/linux/string.h
> @@ -19,54 +19,117 @@ extern void *memdup_user_nul(const void __user *, size_t);
>    */
>   #include <asm/string.h>
>   
> +#if defined(CONFIG_KASAN) && !defined(__SANITIZE_ADDRESS__)
> +/*
> + * For files that are not instrumented (e.g. mm/slub.c) we
> + * should use not instrumented version of mem* functions.
> + */
> +#define memset16	__memset16
> +#define memset32	__memset32
> +#define memset64	__memset64
> +#define memzero_explicit	__memzero_explicit
> +#define strcpy		__strcpy
> +#define strncpy		__strncpy
> +#define strlcpy		__strlcpy
> +#define strscpy		__strscpy
> +#define strcat		__strcat
> +#define strncat		__strncat
> +#define strlcat		__strlcat
> +#define strcmp		__strcmp
> +#define strncmp		__strncmp
> +#define strcasecmp	__strcasecmp
> +#define strncasecmp	__strncasecmp
> +#define strchr		__strchr
> +#define strchrnul	__strchrnul
> +#define strrchr		__strrchr
> +#define strnchr		__strnchr
> +#define skip_spaces	__skip_spaces
> +#define strim		__strim
> +#define strstr		__strstr
> +#define strnstr		__strnstr
> +#define strlen		__strlen
> +#define strnlen		__strnlen
> +#define strpbrk		__strpbrk
> +#define strsep		__strsep
> +#define strspn		__strspn
> +#define strcspn		__strcspn
> +#define memscan		__memscan
> +#define memcmp		__memcmp
> +#define memchr		__memchr
> +#define memchr_inv	__memchr_inv
> +#define strreplace	__strreplace
> +
> +#ifndef __NO_FORTIFY
> +#define __NO_FORTIFY /* FORTIFY_SOURCE uses __builtin_memcpy, etc. */
> +#endif
> +
> +#endif
> +
>   #ifndef __HAVE_ARCH_STRCPY
>   extern char * strcpy(char *,const char *);
> +char *__strcpy(char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRNCPY
>   extern char * strncpy(char *,const char *, __kernel_size_t);
> +char *__strncpy(char *, const char *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRLCPY
>   size_t strlcpy(char *, const char *, size_t);
> +size_t __strlcpy(char *, const char *, size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRSCPY
>   ssize_t strscpy(char *, const char *, size_t);
> +ssize_t __strscpy(char *, const char *, size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRCAT
>   extern char * strcat(char *, const char *);
> +char *__strcat(char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRNCAT
>   extern char * strncat(char *, const char *, __kernel_size_t);
> +char *__strncat(char *, const char *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRLCAT
>   extern size_t strlcat(char *, const char *, __kernel_size_t);
> +size_t __strlcat(char *, const char *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRCMP
>   extern int strcmp(const char *,const char *);
> +int __strcmp(const char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRNCMP
>   extern int strncmp(const char *,const char *,__kernel_size_t);
> +int __strncmp(const char *, const char *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRCASECMP
>   extern int strcasecmp(const char *s1, const char *s2);
> +int __strcasecmp(const char *s1, const char *s2);
>   #endif
>   #ifndef __HAVE_ARCH_STRNCASECMP
>   extern int strncasecmp(const char *s1, const char *s2, size_t n);
> +int __strncasecmp(const char *s1, const char *s2, size_t n);
>   #endif
>   #ifndef __HAVE_ARCH_STRCHR
>   extern char * strchr(const char *,int);
> +char *__strchr(const char *, int);
>   #endif
>   #ifndef __HAVE_ARCH_STRCHRNUL
>   extern char * strchrnul(const char *,int);
> +char *__strchrnul(const char *, int);
>   #endif
>   #ifndef __HAVE_ARCH_STRNCHR
>   extern char * strnchr(const char *, size_t, int);
> +char *__strnchr(const char *, size_t, int);
>   #endif
>   #ifndef __HAVE_ARCH_STRRCHR
>   extern char * strrchr(const char *,int);
> +char *__strrchr(const char *, int);
>   #endif
>   extern char * __must_check skip_spaces(const char *);
> +char * __must_check __skip_spaces(const char *);
>   
>   extern char *strim(char *);
> +char *__strim(char *);
>   
>   static inline __must_check char *strstrip(char *str)
>   {
> @@ -75,27 +138,35 @@ static inline __must_check char *strstrip(char *str)
>   
>   #ifndef __HAVE_ARCH_STRSTR
>   extern char * strstr(const char *, const char *);
> +char *__strstr(const char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRNSTR
>   extern char * strnstr(const char *, const char *, size_t);
> +char *__strnstr(const char *, const char *, size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRLEN
>   extern __kernel_size_t strlen(const char *);
> +__kernel_size_t __strlen(const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRNLEN
>   extern __kernel_size_t strnlen(const char *,__kernel_size_t);
> +__kernel_size_t __strnlen(const char *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_STRPBRK
>   extern char * strpbrk(const char *,const char *);
> +char *__strpbrk(const char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRSEP
>   extern char * strsep(char **,const char *);
> +char *__strsep(char **, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRSPN
>   extern __kernel_size_t strspn(const char *,const char *);
> +__kernel_size_t __strspn(const char *, const char *);
>   #endif
>   #ifndef __HAVE_ARCH_STRCSPN
>   extern __kernel_size_t strcspn(const char *,const char *);
> +__kernel_size_t __strcspn(const char *, const char *);
>   #endif
>   
>   #ifndef __HAVE_ARCH_MEMSET
> @@ -104,14 +175,17 @@ extern void * memset(void *,int,__kernel_size_t);
>   
>   #ifndef __HAVE_ARCH_MEMSET16
>   extern void *memset16(uint16_t *, uint16_t, __kernel_size_t);
> +void *__memset16(uint16_t *, uint16_t, __kernel_size_t);
>   #endif
>   
>   #ifndef __HAVE_ARCH_MEMSET32
>   extern void *memset32(uint32_t *, uint32_t, __kernel_size_t);
> +void *__memset32(uint32_t *, uint32_t, __kernel_size_t);
>   #endif
>   
>   #ifndef __HAVE_ARCH_MEMSET64
>   extern void *memset64(uint64_t *, uint64_t, __kernel_size_t);
> +void *__memset64(uint64_t *, uint64_t, __kernel_size_t);
>   #endif
>   
>   static inline void *memset_l(unsigned long *p, unsigned long v,
> @@ -146,12 +220,15 @@ extern void * memmove(void *,const void *,__kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_MEMSCAN
>   extern void * memscan(void *,int,__kernel_size_t);
> +void *__memscan(void *, int, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_MEMCMP
>   extern int memcmp(const void *,const void *,__kernel_size_t);
> +int __memcmp(const void *, const void *, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_MEMCHR
>   extern void * memchr(const void *,int,__kernel_size_t);
> +void *__memchr(const void *, int, __kernel_size_t);
>   #endif
>   #ifndef __HAVE_ARCH_MEMCPY_MCSAFE
>   static inline __must_check unsigned long memcpy_mcsafe(void *dst,
> @@ -168,7 +245,9 @@ static inline void memcpy_flushcache(void *dst, const void *src, size_t cnt)
>   }
>   #endif
>   void *memchr_inv(const void *s, int c, size_t n);
> +void *__memchr_inv(const void *s, int c, size_t n);
>   char *strreplace(char *s, char old, char new);
> +char *__strreplace(char *s, char old, char new);
>   
>   extern void kfree_const(const void *x);
>   
> diff --git a/lib/Makefile b/lib/Makefile
> index 30b9b0bfbba9..19d0237f9b9c 100644
> --- a/lib/Makefile
> +++ b/lib/Makefile
> @@ -18,6 +18,8 @@ KCOV_INSTRUMENT_list_debug.o := n
>   KCOV_INSTRUMENT_debugobjects.o := n
>   KCOV_INSTRUMENT_dynamic_debug.o := n
>   
> +KASAN_SANITIZE_string.o := n
> +
>   lib-y := ctype.o string.o string_sysfs.o vsprintf.o cmdline.o \
>   	 rbtree.o radix-tree.o timerqueue.o xarray.o \
>   	 idr.o int_sqrt.o extable.o \
> diff --git a/lib/string.c b/lib/string.c
> index f3886c5175ac..31a253201bba 100644
> --- a/lib/string.c
> +++ b/lib/string.c
> @@ -85,7 +85,9 @@ EXPORT_SYMBOL(strcasecmp);
>    * @dest: Where to copy the string to
>    * @src: Where to copy the string from
>    */
> +#ifndef CONFIG_KASAN
>   #undef strcpy
> +#endif
>   char *strcpy(char *dest, const char *src)
>   {
>   	char *tmp = dest;
> @@ -243,7 +245,9 @@ EXPORT_SYMBOL(strscpy);
>    * @dest: The string to be appended to
>    * @src: The string to append to it
>    */
> +#ifndef CONFIG_KASAN
>   #undef strcat
> +#endif
>   char *strcat(char *dest, const char *src)
>   {
>   	char *tmp = dest;
> @@ -319,7 +323,9 @@ EXPORT_SYMBOL(strlcat);
>    * @cs: One string
>    * @ct: Another string
>    */
> +#ifndef CONFIG_KASAN
>   #undef strcmp
> +#endif
>   int strcmp(const char *cs, const char *ct)
>   {
>   	unsigned char c1, c2;
> @@ -773,7 +779,9 @@ EXPORT_SYMBOL(memmove);
>    * @ct: Another area of memory
>    * @count: The size of the area.
>    */
> +#ifndef CONFIG_KASAN
>   #undef memcmp
> +#endif
>   __visible int memcmp(const void *cs, const void *ct, size_t count)
>   {
>   	const unsigned char *su1, *su2;
> diff --git a/mm/kasan/string.c b/mm/kasan/string.c
> index 083b967255a2..0db31bbbf643 100644
> --- a/mm/kasan/string.c
> +++ b/mm/kasan/string.c
> @@ -35,6 +35,42 @@ void *memset(void *addr, int c, size_t len)
>   	return __memset(addr, c, len);
>   }
>   
> +#undef memset16
> +void *memset16(uint16_t *s, uint16_t v, size_t count)
> +{
> +	check_memory_region((unsigned long)s, count << 1, true, _RET_IP_);
> +
> +	return __memset16(s, v, count);
> +}
> +EXPORT_SYMBOL(memset16);
> +
> +#undef memset32
> +void *memset32(uint32_t *s, uint32_t v, size_t count)
> +{
> +	check_memory_region((unsigned long)s, count << 2, true, _RET_IP_);
> +
> +	return __memset32(s, v, count);
> +}
> +EXPORT_SYMBOL(memset32);
> +
> +#undef memset64
> +void *memset64(uint64_t *s, uint64_t v, size_t count)
> +{
> +	check_memory_region((unsigned long)s, count << 3, true, _RET_IP_);
> +
> +	return __memset64(s, v, count);
> +}
> +EXPORT_SYMBOL(memset64);
> +
> +#undef memzero_explicit
> +void memzero_explicit(void *s, size_t count)
> +{
> +	check_memory_region((unsigned long)s, count, true, _RET_IP_);
> +
> +	return __memzero_explicit(s, count);
> +}
> +EXPORT_SYMBOL(memzero_explicit);
> +
>   #undef memmove
>   void *memmove(void *dest, const void *src, size_t len)
>   {
> @@ -52,3 +88,361 @@ void *memcpy(void *dest, const void *src, size_t len)
>   
>   	return __memcpy(dest, src, len);
>   }
> +
> +#undef strcpy
> +char *strcpy(char *dest, const char *src)
> +{
> +	size_t len = __strlen(src) + 1;
> +
> +	check_memory_region((unsigned long)src, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, len, true, _RET_IP_);
> +
> +	return __strcpy(dest, src);
> +}
> +EXPORT_SYMBOL(strcpy);
> +
> +#undef strncpy
> +char *strncpy(char *dest, const char *src, size_t count)
> +{
> +	size_t len = min(__strlen(src) + 1, count);
> +
> +	check_memory_region((unsigned long)src, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, count, true, _RET_IP_);
> +
> +	return __strncpy(dest, src, count);
> +}
> +EXPORT_SYMBOL(strncpy);
> +
> +#undef strlcpy
> +size_t strlcpy(char *dest, const char *src, size_t size)
> +{
> +	size_t len = __strlen(src) + 1;
> +
> +	check_memory_region((unsigned long)src, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, min(len, size), true, _RET_IP_);
> +
> +	return __strlcpy(dest, src, size);
> +}
> +EXPORT_SYMBOL(strlcpy);
> +
> +#undef strscpy
> +ssize_t strscpy(char *dest, const char *src, size_t count)
> +{
> +	int len = min(__strlen(src) + 1, count);
> +
> +	check_memory_region((unsigned long)src, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, len, true, _RET_IP_);
> +
> +	return __strscpy(dest, src, count);
> +}
> +EXPORT_SYMBOL(strscpy);
> +
> +#undef strcat
> +char *strcat(char *dest, const char *src)
> +{
> +	size_t slen = __strlen(src) + 1;
> +	size_t dlen = __strlen(dest);
> +
> +	check_memory_region((unsigned long)src, slen, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
> +	check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
> +
> +	return __strcat(dest, src);
> +}
> +EXPORT_SYMBOL(strcat);
> +
> +#undef strncat
> +char *strncat(char *dest, const char *src, size_t count)
> +{
> +	size_t slen = min(__strlen(src) + 1, count);
> +	size_t dlen = __strlen(dest);
> +
> +	check_memory_region((unsigned long)src, slen, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
> +	check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
> +
> +	return __strncat(dest, src, count);
> +}
> +EXPORT_SYMBOL(strncat);
> +
> +#undef strlcat
> +size_t strlcat(char *dest, const char *src, size_t count)
> +{
> +	size_t slen = min(__strlen(src) + 1, count);
> +	size_t dlen = __strlen(dest);
> +
> +	check_memory_region((unsigned long)src, slen, false, _RET_IP_);
> +	check_memory_region((unsigned long)dest, dlen, false, _RET_IP_);
> +	check_memory_region((unsigned long)(dest + dlen), slen, true, _RET_IP_);
> +
> +	return __strlcat(dest, src, count);
> +}
> +EXPORT_SYMBOL(strlcat);
> +
> +#undef strcmp
> +int strcmp(const char *cs, const char *ct)
> +{
> +	size_t len = min(__strlen(cs) + 1, __strlen(ct) + 1);
> +
> +	check_memory_region((unsigned long)cs, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)ct, len, false, _RET_IP_);
> +
> +	return __strcmp(cs, ct);
> +}
> +EXPORT_SYMBOL(strcmp);
> +
> +#undef strncmp
> +int strncmp(const char *cs, const char *ct, size_t count)
> +{
> +	size_t len = min3(__strlen(cs) + 1, __strlen(ct) + 1, count);
> +
> +	check_memory_region((unsigned long)cs, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)ct, len, false, _RET_IP_);
> +
> +	return __strncmp(cs, ct, count);
> +}
> +EXPORT_SYMBOL(strncmp);
> +
> +#undef strcasecmp
> +int strcasecmp(const char *s1, const char *s2)
> +{
> +	size_t len = min(__strlen(s1) + 1, __strlen(s2) + 1);
> +
> +	check_memory_region((unsigned long)s1, len, false, _RET_IP_);
> +	check_memory_region((unsigned long)s2, len, false, _RET_IP_);
> +
> +	return __strcasecmp(s1, s2);
> +}
> +EXPORT_SYMBOL(strcasecmp);
> +
> +#undef strncasecmp
> +int strncasecmp(const char *s1, const char *s2, size_t len)
> +{
> +	size_t sz = min3(__strlen(s1) + 1, __strlen(s2) + 1, len);
> +
> +	check_memory_region((unsigned long)s1, sz, false, _RET_IP_);
> +	check_memory_region((unsigned long)s2, sz, false, _RET_IP_);
> +
> +	return __strncasecmp(s1, s2, len);
> +}
> +EXPORT_SYMBOL(strncasecmp);
> +
> +#undef strchr
> +char *strchr(const char *s, int c)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, false, _RET_IP_);
> +
> +	return __strchr(s, c);
> +}
> +EXPORT_SYMBOL(strchr);
> +
> +#undef strchrnul
> +char *strchrnul(const char *s, int c)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, false, _RET_IP_);
> +
> +	return __strchrnul(s, c);
> +}
> +EXPORT_SYMBOL(strchrnul);
> +
> +#undef strrchr
> +char *strrchr(const char *s, int c)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, false, _RET_IP_);
> +
> +	return __strrchr(s, c);
> +}
> +EXPORT_SYMBOL(strrchr);
> +
> +#undef strnchr
> +char *strnchr(const char *s, size_t count, int c)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, false, _RET_IP_);
> +
> +	return __strnchr(s, count, c);
> +}
> +EXPORT_SYMBOL(strnchr);
> +
> +#undef skip_spaces
> +char *skip_spaces(const char *str)
> +{
> +	size_t len = __strlen(str) + 1;
> +
> +	check_memory_region((unsigned long)str, len, false, _RET_IP_);
> +
> +	return __skip_spaces(str);
> +}
> +EXPORT_SYMBOL(skip_spaces);
> +
> +#undef strim
> +char *strim(char *s)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, false, _RET_IP_);
> +
> +	return __strim(s);
> +}
> +EXPORT_SYMBOL(strim);
> +
> +#undef strstr
> +char *strstr(const char *s1, const char *s2)
> +{
> +	size_t l1 = __strlen(s1) + 1;
> +	size_t l2 = __strlen(s2) + 1;
> +
> +	check_memory_region((unsigned long)s1, l1, false, _RET_IP_);
> +	check_memory_region((unsigned long)s2, l2, false, _RET_IP_);
> +
> +	return __strstr(s1, s2);
> +}
> +EXPORT_SYMBOL(strstr);
> +
> +#undef strnstr
> +char *strnstr(const char *s1, const char *s2, size_t len)
> +{
> +	size_t l1 = min(__strlen(s1) + 1, len);
> +	size_t l2 = __strlen(s2) + 1;
> +
> +	check_memory_region((unsigned long)s1, l1, false, _RET_IP_);
> +	check_memory_region((unsigned long)s2, l2, false, _RET_IP_);
> +
> +	return __strnstr(s1, s2, len);
> +}
> +EXPORT_SYMBOL(strnstr);
> +
> +#undef strlen
> +size_t strlen(const char *s)
> +{
> +	size_t len = __strlen(s);
> +
> +	check_memory_region((unsigned long)s, len + 1, false, _RET_IP_);
> +
> +	return len;
> +}
> +EXPORT_SYMBOL(strlen);
> +
> +#undef strnlen
> +size_t strnlen(const char *s, size_t count)
> +{
> +	size_t len = __strnlen(s, count);
> +
> +	check_memory_region((unsigned long)s, min(len + 1, count), false, _RET_IP_);
> +
> +	return len;
> +}
> +EXPORT_SYMBOL(strnlen);
> +
> +#undef strpbrk
> +char *strpbrk(const char *cs, const char *ct)
> +{
> +	size_t ls = __strlen(cs) + 1;
> +	size_t lt = __strlen(ct) + 1;
> +
> +	check_memory_region((unsigned long)cs, ls, false, _RET_IP_);
> +	check_memory_region((unsigned long)ct, lt, false, _RET_IP_);
> +
> +	return __strpbrk(cs, ct);
> +}
> +EXPORT_SYMBOL(strpbrk);
> +
> +#undef strsep
> +char *strsep(char **s, const char *ct)
> +{
> +	char *cs = *s;
> +
> +	check_memory_region((unsigned long)s, sizeof(*s), true, _RET_IP_);
> +
> +	if (cs) {
> +		int ls = __strlen(cs) + 1;
> +		int lt = __strlen(ct) + 1;
> +
> +		check_memory_region((unsigned long)cs, ls, false, _RET_IP_);
> +		check_memory_region((unsigned long)ct, lt, false, _RET_IP_);
> +	}
> +
> +	return __strsep(s, ct);
> +}
> +EXPORT_SYMBOL(strsep);
> +
> +#undef strspn
> +size_t strspn(const char *s, const char *accept)
> +{
> +	size_t ls = __strlen(s) + 1;
> +	size_t la = __strlen(accept) + 1;
> +
> +	check_memory_region((unsigned long)s, ls, false, _RET_IP_);
> +	check_memory_region((unsigned long)accept, la, false, _RET_IP_);
> +
> +	return __strspn(s, accept);
> +}
> +EXPORT_SYMBOL(strspn);
> +
> +#undef strcspn
> +size_t strcspn(const char *s, const char *reject)
> +{
> +	size_t ls = __strlen(s) + 1;
> +	size_t lr = __strlen(reject) + 1;
> +
> +	check_memory_region((unsigned long)s, ls, false, _RET_IP_);
> +	check_memory_region((unsigned long)reject, lr, false, _RET_IP_);
> +
> +	return __strcspn(s, reject);
> +}
> +EXPORT_SYMBOL(strcspn);
> +
> +#undef memscan
> +void *memscan(void *addr, int c, size_t size)
> +{
> +	check_memory_region((unsigned long)addr, size, false, _RET_IP_);
> +
> +	return __memscan(addr, c, size);
> +}
> +EXPORT_SYMBOL(memscan);
> +
> +#undef memcmp
> +int memcmp(const void *cs, const void *ct, size_t count)
> +{
> +	check_memory_region((unsigned long)cs, count, false, _RET_IP_);
> +	check_memory_region((unsigned long)ct, count, false, _RET_IP_);
> +
> +	return __memcmp(cs, ct, count);
> +}
> +EXPORT_SYMBOL(memcmp);
> +
> +#undef memchr
> +void *memchr(const void *s, int c, size_t n)
> +{
> +	check_memory_region((unsigned long)s, n, false, _RET_IP_);
> +
> +	return __memchr(s, c, n);
> +}
> +EXPORT_SYMBOL(memchr);
> +
> +#undef memchr_inv
> +void *memchr_inv(const void *start, int c, size_t bytes)
> +{
> +	check_memory_region((unsigned long)start, bytes, false, _RET_IP_);
> +
> +	return __memchr_inv(start, c, bytes);
> +}
> +EXPORT_SYMBOL(memchr_inv);
> +
> +#undef strreplace
> +char *strreplace(char *s, char old, char new)
> +{
> +	size_t len = __strlen(s) + 1;
> +
> +	check_memory_region((unsigned long)s, len, true, _RET_IP_);
> +
> +	return __strreplace(s, old, new);
> +}
> +EXPORT_SYMBOL(strreplace);
>