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author | Alexey Dobriyan <adobriyan@gmail.com> | 2006-09-30 23:27:20 -0700 |
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committer | Linus Torvalds <torvalds@g5.osdl.org> | 2006-10-01 00:39:19 -0700 |
commit | 1a2f67b459bb7846d4a15924face63eb2683acc2 (patch) | |
tree | 4c010d4c4220c9523342fb0daac90a433f36b53e /fs/posix_acl.c | |
parent | 9442e691e4aec85eba43ac60a3e77c77fd2e73a4 (diff) | |
download | linux-3.10-1a2f67b459bb7846d4a15924face63eb2683acc2.tar.gz linux-3.10-1a2f67b459bb7846d4a15924face63eb2683acc2.tar.bz2 linux-3.10-1a2f67b459bb7846d4a15924face63eb2683acc2.zip |
[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>
Diffstat (limited to 'fs/posix_acl.c')
0 files changed, 0 insertions, 0 deletions