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linux/arch/arm/boot/compressed/string.c
Kees Cook cfecea6ead lib/string: Move helper functions out of string.c
The core functions of string.c are those that may be implemented by
per-architecture functions, or overloaded by FORTIFY_SOURCE. As a
result, it needs to be built with __NO_FORTIFY. Without this, macros
will collide with function declarations. This was accidentally working
due to -ffreestanding (on some architectures). Make this deterministic
by explicitly setting __NO_FORTIFY and move all the helper functions
into string_helpers.c so that they gain the fortification coverage they
had been missing.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Cc: Andy Lavr <andy.lavr@gmail.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Bartosz Golaszewski <bgolaszewski@baylibre.com>
Acked-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
2021-09-25 08:20:49 -07:00

163 lines
2.9 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* arch/arm/boot/compressed/string.c
*
* Small subset of simple string routines
*/
#define __NO_FORTIFY
#include <linux/string.h>
/*
* The decompressor is built without KASan but uses the same redirects as the
* rest of the kernel when CONFIG_KASAN is enabled, defining e.g. memcpy()
* to __memcpy() but since we are not linking with the main kernel string
* library in the decompressor, that will lead to link failures.
*
* Undefine KASan's versions, define the wrapped functions and alias them to
* the right names so that when e.g. __memcpy() appear in the code, it will
* still be linked to this local version of memcpy().
*/
#ifdef CONFIG_KASAN
#undef memcpy
#undef memmove
#undef memset
void *__memcpy(void *__dest, __const void *__src, size_t __n) __alias(memcpy);
void *__memmove(void *__dest, __const void *__src, size_t count) __alias(memmove);
void *__memset(void *s, int c, size_t count) __alias(memset);
#endif
void *memcpy(void *__dest, __const void *__src, size_t __n)
{
int i = 0;
unsigned char *d = (unsigned char *)__dest, *s = (unsigned char *)__src;
for (i = __n >> 3; i > 0; i--) {
*d++ = *s++;
*d++ = *s++;
*d++ = *s++;
*d++ = *s++;
*d++ = *s++;
*d++ = *s++;
*d++ = *s++;
*d++ = *s++;
}
if (__n & 1 << 2) {
*d++ = *s++;
*d++ = *s++;
*d++ = *s++;
*d++ = *s++;
}
if (__n & 1 << 1) {
*d++ = *s++;
*d++ = *s++;
}
if (__n & 1)
*d++ = *s++;
return __dest;
}
void *memmove(void *__dest, __const void *__src, size_t count)
{
unsigned char *d = __dest;
const unsigned char *s = __src;
if (__dest == __src)
return __dest;
if (__dest < __src)
return memcpy(__dest, __src, count);
while (count--)
d[count] = s[count];
return __dest;
}
size_t strlen(const char *s)
{
const char *sc = s;
while (*sc != '\0')
sc++;
return sc - s;
}
size_t strnlen(const char *s, size_t count)
{
const char *sc;
for (sc = s; count-- && *sc != '\0'; ++sc)
/* nothing */;
return sc - s;
}
int memcmp(const void *cs, const void *ct, size_t count)
{
const unsigned char *su1 = cs, *su2 = ct, *end = su1 + count;
int res = 0;
while (su1 < end) {
res = *su1++ - *su2++;
if (res)
break;
}
return res;
}
int strcmp(const char *cs, const char *ct)
{
unsigned char c1, c2;
int res = 0;
do {
c1 = *cs++;
c2 = *ct++;
res = c1 - c2;
if (res)
break;
} while (c1);
return res;
}
void *memchr(const void *s, int c, size_t count)
{
const unsigned char *p = s;
while (count--)
if ((unsigned char)c == *p++)
return (void *)(p - 1);
return NULL;
}
char *strchr(const char *s, int c)
{
while (*s != (char)c)
if (*s++ == '\0')
return NULL;
return (char *)s;
}
char *strrchr(const char *s, int c)
{
const char *last = NULL;
do {
if (*s == (char)c)
last = s;
} while (*s++);
return (char *)last;
}
#undef memset
void *memset(void *s, int c, size_t count)
{
char *xs = s;
while (count--)
*xs++ = c;
return s;
}