Commit 95cadae3 authored by Qian Cai's avatar Qian Cai Committed by Kees Cook
Browse files

fortify: strlen: Avoid shadowing previous locals 



The __compiletime_strlen() macro expansion will shadow p_size and p_len
local variables. No callers currently use any of the shadowed names
for their "p" variable, so there are no code generation problems.

Add "__" prefixes to variable definitions __compiletime_strlen() to
avoid new W=2 warnings:

./include/linux/fortify-string.h: In function 'strnlen':
./include/linux/fortify-string.h:17:9: warning: declaration of 'p_size' shadows a previous local [-Wshadow]
   17 |  size_t p_size = __builtin_object_size(p, 1); \
      |         ^~~~~~
./include/linux/fortify-string.h:77:17: note: in expansion of macro '__compiletime_strlen'
   77 |  size_t p_len = __compiletime_strlen(p);
      |                 ^~~~~~~~~~~~~~~~~~~~
./include/linux/fortify-string.h:76:9: note: shadowed declaration is here
   76 |  size_t p_size = __builtin_object_size(p, 1);
      |         ^~~~~~

Signed-off-by: default avatarQian Cai <quic_qiancai@quicinc.com>
Signed-off-by: default avatarKees Cook <keescook@chromium.org>
Link: https://lore.kernel.org/r/20211025210528.261643-1-quic_qiancai@quicinc.com
parent 9a48e756

include/linux/fortify-string.h

+12 −12
Original line number Diff line number Diff line
@@ -13,15 +13,15 @@ void __write_overflow(void) __compiletime_error("detected write beyond size of o 
#define __compiletime_strlen(p)					\

({								\

	unsigned char *__p = (unsigned char *)(p);		\

	size_t ret = (size_t)-1;			\

	size_t p_size = __builtin_object_size(p, 1);	\

	if (p_size != (size_t)-1) {			\

		size_t p_len = p_size - 1;		\

		if (__builtin_constant_p(__p[p_len]) &&	\

		    __p[p_len] == '\0')			\

			ret = __builtin_strlen(__p);	\

	size_t __ret = (size_t)-1;				\

	size_t __p_size = __builtin_object_size(p, 1);		\

	if (__p_size != (size_t)-1) {				\

		size_t __p_len = __p_size - 1;			\

		if (__builtin_constant_p(__p[__p_len]) &&	\

		    __p[__p_len] == '\0')			\

			__ret = __builtin_strlen(__p);		\

	}							\

	ret;						\

	__ret;							\

})



#if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)