linux-hardening - [PATCH] fortify: Avoid shadowing previous locals

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Date:   Mon, 25 Oct 2021 14:37:28 -0400
From:   Qian Cai <quic_qiancai@...cinc.com>
To:     Kees Cook <keescook@...omium.org>
CC:     <linux-hardening@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "Qian Cai" <quic_qiancai@...cinc.com>
Subject: [PATCH] fortify: Avoid shadowing previous locals

__compiletime_strlen macro expansion will shadow p_size and p_len local
variables. Just rename those in __compiletime_strlen.

Signed-off-by: Qian Cai <quic_qiancai@...cinc.com>
---
 include/linux/fortify-string.h | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/include/linux/fortify-string.h b/include/linux/fortify-string.h
index fdb0a74c9ca2..155c622e4f24 100644
--- a/include/linux/fortify-string.h
+++ b/include/linux/fortify-string.h
@@ -10,18 +10,18 @@ void __read_overflow(void) __compiletime_error("detected read beyond size of obj
 void __read_overflow2(void) __compiletime_error("detected read beyond size of object (2nd parameter)");
 void __write_overflow(void) __compiletime_error("detected write beyond size of object (1st parameter)");
 
-#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);	\
-	}						\
-	ret;						\
+#define __compiletime_strlen(ptr)				\
+({								\
+	unsigned char *__ptr = (unsigned char *)(ptr);		\
+	size_t ret = (size_t)-1;				\
+	size_t ptr_size = __builtin_object_size(ptr, 1);	\
+	if (ptr_size != (size_t)-1) {				\
+		size_t ptr_len = ptr_size - 1;			\
+		if (__builtin_constant_p(__ptr[ptr_len]) &&	\
+		    __ptr[ptr_len] == '\0')			\
+			ret = __builtin_strlen(__ptr);		\
+	}							\
+	ret;							\
 })
 
 #if defined(CONFIG_KASAN_GENERIC) || defined(CONFIG_KASAN_SW_TAGS)
-- 
2.30.2