From 1a2f67b459bb7846d4a15924face63eb2683acc2 Mon Sep 17 00:00:00 2001 From: Alexey Dobriyan Date: Sat, 30 Sep 2006 23:27:20 -0700 Subject: [PATCH] kmemdup: introduce One of idiomatic ways to duplicate a region of memory is dst = kmalloc(len, GFP_KERNEL); if (!dst) return -ENOMEM; memcpy(dst, src, len); which is neat code except a programmer needs to write size twice. Which sometimes leads to mistakes. If len passed to kmalloc is smaller that len passed to memcpy, it's straight overwrite-beyond-end. If len passed to memcpy is smaller than len passed to kmalloc, it's either a) legit behaviour ;-), or b) cloned buffer will contain garbage in second half. Slight trolling of commit lists shows several duplications bugs done exactly because of diverged lenghts: Linux: [CRYPTO]: Fix memcpy/memset args. [PATCH] memcpy/memset fixes OpenBSD: kerberosV/src/lib/asn1: der_copy.c:1.4 If programmer is given only one place to play with lengths, I believe, such mistakes could be avoided. With kmemdup, the snippet above will be rewritten as: dst = kmemdup(src, len, GFP_KERNEL); if (!dst) return -ENOMEM; This also leads to smaller code (kzalloc effect). Quick grep shows 200+ places where kmemdup() can be used. Signed-off-by: Alexey Dobriyan Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- include/linux/string.h | 1 + 1 file changed, 1 insertion(+) (limited to 'include/linux/string.h') diff --git a/include/linux/string.h b/include/linux/string.h index e4c755860316..4f69ef9e6eb5 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -99,6 +99,7 @@ extern void * memchr(const void *,int,__kernel_size_t); #endif extern char *kstrdup(const char *s, gfp_t gfp); +extern void *kmemdup(const void *src, size_t len, gfp_t gfp); #ifdef __cplusplus } -- cgit v1.2.3