From 9e4a617757273a86b560c1ece40c48e4940a3c79 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Thu, 29 Sep 2022 02:24:53 -0700 Subject: [PATCH] string: Add __realloc_size hint to kmemdup() Add __realloc_size() hint to kmemdup() so the compiler can reason about the length of the returned buffer. (These must not use __alloc_size, since those include __malloc which says the contents aren't defined[1]). [1] https://lore.kernel.org/linux-hardening/d199c2af-06af-8a50-a6a1-00eefa0b67b4@prevas.dk/ Cc: Rasmus Villemoes Cc: Guenter Roeck Cc: Andy Shevchenko Cc: Paolo Abeni Cc: Geert Uytterhoeven Signed-off-by: Kees Cook --- include/linux/fortify-string.h | 3 ++- include/linux/string.h | 2 +- 2 files changed, 3 insertions(+), 2 deletions(-) diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h index e5b39b1..49782f6 100644 --- a/include/linux/fortify-string.h +++ b/include/linux/fortify-string.h @@ -659,7 +659,8 @@ __FORTIFY_INLINE void *memchr_inv(const void * const POS0 p, int c, size_t size) return __real_memchr_inv(p, c, size); } -extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup); +extern void *__real_kmemdup(const void *src, size_t len, gfp_t gfp) __RENAME(kmemdup) + __realloc_size(2); __FORTIFY_INLINE void *kmemdup(const void * const POS0 p, size_t size, gfp_t gfp) { size_t p_size = __struct_size(p); diff --git a/include/linux/string.h b/include/linux/string.h index cf7607b..db28802 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -176,7 +176,7 @@ extern void kfree_const(const void *x); extern char *kstrdup(const char *s, gfp_t gfp) __malloc; extern const char *kstrdup_const(const char *s, gfp_t gfp); extern char *kstrndup(const char *s, size_t len, gfp_t gfp); -extern void *kmemdup(const void *src, size_t len, gfp_t gfp); +extern void *kmemdup(const void *src, size_t len, gfp_t gfp) __realloc_size(2); extern char *kmemdup_nul(const char *s, size_t len, gfp_t gfp); extern char **argv_split(gfp_t gfp, const char *str, int *argcp); -- 2.7.4