[merged] string-use-__builtin_memcpy-in-strlcpy-strlcat.patch removed from -mm tree

[Andrew Morton <akpm@linux-foundation.org>]

The quilt patch titled
     Subject: string: use __builtin_memcpy() in strlcpy/strlcat
has been removed from the -mm tree.  Its filename was
     string-use-__builtin_memcpy-in-strlcpy-strlcat.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Alexander Potapenko <glider@google.com>
Subject: string: use __builtin_memcpy() in strlcpy/strlcat
Date: Tue, 30 May 2023 10:39:11 +0200

lib/string.c is built with -ffreestanding, which prevents the compiler
from replacing certain functions with calls to their library versions.

On the other hand, this also prevents Clang and GCC from instrumenting
calls to memcpy() when building with KASAN, KCSAN or KMSAN:
 - KASAN normally replaces memcpy() with __asan_memcpy() with the
   additional cc-param,asan-kernel-mem-intrinsic-prefix=1;
 - KCSAN and KMSAN replace memcpy() with __tsan_memcpy() and
   __msan_memcpy() by default.

To let the tools catch memory accesses from strlcpy/strlcat, replace the
calls to memcpy() with __builtin_memcpy(), which KASAN, KCSAN and KMSAN
are able to replace even in -ffreestanding mode.

This preserves the behavior in normal builds (__builtin_memcpy() ends up
being replaced with memcpy()), and does not introduce new instrumentation
in unwanted places, as strlcpy/strlcat are already instrumented.

Link: https://lkml.kernel.org/r/20230530083911.1104336-1-glider@google.com
Link: https://lore.kernel.org/all/20230224085942.1791837-1-elver@google.com/
Signed-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Marco Elver <elver@google.com>
Acked-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Andy Shevchenko <andy@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Cc: Nick Desaulniers <ndesaulniers@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 lib/string.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- a/lib/string.c~string-use-__builtin_memcpy-in-strlcpy-strlcat
+++ a/lib/string.c
@@ -110,7 +110,7 @@ size_t strlcpy(char *dest, const char *s
 
 	if (size) {
 		size_t len = (ret >= size) ? size - 1 : ret;
-		memcpy(dest, src, len);
+		__builtin_memcpy(dest, src, len);
 		dest[len] = '\0';
 	}
 	return ret;
@@ -260,7 +260,7 @@ size_t strlcat(char *dest, const char *s
 	count -= dsize;
 	if (len >= count)
 		len = count-1;
-	memcpy(dest, src, len);
+	__builtin_memcpy(dest, src, len);
 	dest[len] = 0;
 	return res;
 }
_

Patches currently in -mm which might be from glider@google.com are