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authorAlexey Dobriyan <adobriyan@gmail.com>2006-10-01 10:27:20 +0400
committerLinus Torvalds <torvalds@g5.osdl.org>2006-10-01 11:39:19 +0400
commit1a2f67b459bb7846d4a15924face63eb2683acc2 (patch)
tree4c010d4c4220c9523342fb0daac90a433f36b53e /fs/posix_acl.c
parent9442e691e4aec85eba43ac60a3e77c77fd2e73a4 (diff)
downloadlinux-1a2f67b459bb7846d4a15924face63eb2683acc2.tar.xz
[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 <adobriyan@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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