[PATCH 6.0 0577/1073] fortify: Use SIZE_MAX instead of (size_t)-1

Greg Kroah-Hartman
2022-12-28T16:08:43Z

From: Kees Cook <keescook@chromium.org>

[ Upstream commit 311fb40aa0569abacc430b0d66ee41470803111f ]

Clean up uses of "(size_t)-1" in favor of SIZE_MAX.

Cc: linux-hardening@vger.kernel.org
Suggested-by: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Stable-dep-of: e9a40e1585d7 ("fortify: Do not cast to "unsigned char"")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
include/linux/fortify-string.h | 29 +++++++++++++++--------------
1 file changed, 15 insertions(+), 14 deletions(-)

diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
index fce2fb2fc962..ae076aae9e66 100644
--- a/include/linux/fortify-string.h
+++ b/include/linux/fortify-string.h
@@ -3,6 +3,7 @@
#define _LINUX_FORTIFY_STRING_H_

#include <linux/const.h>
+#include <linux/limits.h>

#define __FORTIFY_INLINE extern __always_inline __gnu_inline __overloadable
#define __RENAME(x) __asm__(#x)
@@ -17,9 +18,9 @@ void __write_overflow_field(size_t avail, size_t wanted) __compiletime_warning("
#define __compiletime_strlen(p) \
({ \
unsigned char *__p = (unsigned char *)(p); \
- size_t __ret = (size_t)-1; \
+ size_t __ret = SIZE_MAX; \
size_t __p_size = __builtin_object_size(p, 1); \
- if (__p_size != (size_t)-1 && \
+ if (__p_size != SIZE_MAX && \
__builtin_constant_p(*__p)) { \
size_t __p_len = __p_size - 1; \
if (__builtin_constant_p(__p[__p_len]) && \
@@ -95,7 +96,7 @@ char *strcat(char * const POS p, const char *q)
{
size_t p_size = __builtin_object_size(p, 1);

- if (p_size == (size_t)-1)
+ if (p_size == SIZE_MAX)
return __underlying_strcat(p, q);
if (strlcat(p, q, p_size) >= p_size)
fortify_panic(__func__);
@@ -110,7 +111,7 @@ __FORTIFY_INLINE __kernel_size_t strnlen(const char * const POS p, __kernel_size
size_t ret;

/* We can take compile-time actions when maxlen is const. */
- if (__builtin_constant_p(maxlen) && p_len != (size_t)-1) {
+ if (__builtin_constant_p(maxlen) && p_len != SIZE_MAX) {
/* If p is const, we can use its compile-time-known len. */
if (maxlen >= p_size)
return p_len;
@@ -138,7 +139,7 @@ __kernel_size_t __fortify_strlen(const char * const POS p)
size_t p_size = __builtin_object_size(p, 1);

/* Give up if we don't know how large p is. */
- if (p_size == (size_t)-1)
+ if (p_size == SIZE_MAX)
return __underlying_strlen(p);
ret = strnlen(p, p_size);
if (p_size <= ret)
@@ -155,7 +156,7 @@ __FORTIFY_INLINE size_t strlcpy(char * const POS p, const char * const POS q, si
size_t q_len; /* Full count of source string length. */
size_t len; /* Count of characters going into destination. */

- if (p_size == (size_t)-1 && q_size == (size_t)-1)
+ if (p_size == SIZE_MAX && q_size == SIZE_MAX)
return __real_strlcpy(p, q, size);
q_len = strlen(q);
len = (q_len >= size) ? size - 1 : q_len;
@@ -183,7 +184,7 @@ __FORTIFY_INLINE ssize_t strscpy(char * const POS p, const char * const POS q, s
size_t q_size = __builtin_object_size(q, 1);

/* If we cannot get size of p and q default to call strscpy. */
- if (p_size == (size_t) -1 && q_size == (size_t) -1)
+ if (p_size == SIZE_MAX && q_size == SIZE_MAX)
return __real_strscpy(p, q, size);

/*
@@ -228,7 +229,7 @@ char *strncat(char * const POS p, const char * const POS q, __kernel_size_t coun
size_t p_size = __builtin_object_size(p, 1);
size_t q_size = __builtin_object_size(q, 1);

- if (p_size == (size_t)-1 && q_size == (size_t)-1)
+ if (p_size == SIZE_MAX && q_size == SIZE_MAX)
return __underlying_strncat(p, q, count);
p_len = strlen(p);
copy_len = strnlen(q, count);
@@ -269,10 +270,10 @@ __FORTIFY_INLINE void fortify_memset_chk(__kernel_size_t size,
/*
* Always stop accesses beyond the struct that contains the
* field, when the buffer's remaining size is known.
- * (The -1 test is to optimize away checks where the buffer
+ * (The SIZE_MAX test is to optimize away checks where the buffer
* lengths are unknown.)
*/
- if (p_size != (size_t)(-1) && p_size < size)
+ if (p_size != SIZE_MAX && p_size < size)
fortify_panic("memset");
}

@@ -363,11 +364,11 @@ __FORTIFY_INLINE void fortify_memcpy_chk(__kernel_size_t size,
/*
* Always stop accesses beyond the struct that contains the
* field, when the buffer's remaining size is known.
- * (The -1 test is to optimize away checks where the buffer
+ * (The SIZE_MAX test is to optimize away checks where the buffer
* lengths are unknown.)
*/
- if ((p_size != (size_t)(-1) && p_size < size) ||
- (q_size != (size_t)(-1) && q_size < size))
+ if ((p_size != SIZE_MAX && p_size < size) ||
+ (q_size != SIZE_MAX && q_size < size))
fortify_panic(func);
}

@@ -466,7 +467,7 @@ char *strcpy(char * const POS p, const char * const POS q)
size_t size;

/* If neither buffer size is known, immediately give up. */
- if (p_size == (size_t)-1 && q_size == (size_t)-1)
+ if (p_size == SIZE_MAX && q_size == SIZE_MAX)
return __underlying_strcpy(p, q);
size = strlen(q) + 1;
/* Compile-time check for const size overflow. */
--
2.35.1