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memdup_user(): introduce

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I notice there are many places doing copy_from_user() which follows
kmalloc():

        dst = kmalloc(len, GFP_KERNEL);
        if (!dst)
                return -ENOMEM;
        if (copy_from_user(dst, src, len)) {
		kfree(dst);
		return -EFAULT
	}

memdup_user() is a wrapper of the above code.  With this new function, we
don't have to write 'len' twice, which can lead to typos/mistakes.  It
also produces smaller code and kernel text.

A quick grep shows 250+ places where memdup_user() *may* be used.  I'll
prepare a patchset to do this conversion.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Americo Wang <xiyou.wangcong@gmail.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Li Zefan
2009-03-31 15:23:16 -07:00
committed by Linus Torvalds
parent e2f17d9459
commit 610a77e04a
2 changed files with 31 additions and 0 deletions
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1
include/linux/string.h
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@@ -12,6 +12,7 @@
#include <linux/stddef.h> /* for NULL */
extern char *strndup_user(const char __user *, long);
extern void *memdup_user(const void __user *, size_t);
/*
* Include machine specific inline routines