Messages in this thread Patch in this message | | | Date | Fri, 06 Mar 2009 17:49:45 +0800 | From | Li Zefan <> | Subject | [PATCH -v2] 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.
v1 -> v2: change the name from kmemdup_from_user to memdup_user.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> ---
Can this get into 2.6.29, so I can prepare patches based on linux-next? And this won't cause regression, since no one uses it yet. :)
--- include/linux/string.h | 1 + mm/util.c | 26 ++++++++++++++++++++++++++ 2 files changed, 27 insertions(+), 0 deletions(-)
diff --git a/include/linux/string.h b/include/linux/string.h index 76ec218..79f30f3 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -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, gfp_t); /* * Include machine specific inline routines diff --git a/mm/util.c b/mm/util.c index 37eaccd..3d21c21 100644 --- a/mm/util.c +++ b/mm/util.c @@ -70,6 +70,32 @@ void *kmemdup(const void *src, size_t len, gfp_t gfp) EXPORT_SYMBOL(kmemdup); /** + * memdup_user - duplicate memory region from user space + * + * @src: source address in user space + * @len: number of bytes to copy + * @gfp: GFP mask to use + * + * Returns an ERR_PTR() on failure. + */ +void *memdup_user(const void __user *src, size_t len, gfp_t gfp) +{ + void *p; + + p = kmalloc_track_caller(len, gfp); + if (!p) + return ERR_PTR(-ENOMEM); + + if (copy_from_user(p, src, len)) { + kfree(p); + return ERR_PTR(-EFAULT); + } + + return p; +} +EXPORT_SYMBOL(memdup_user); + +/** * __krealloc - like krealloc() but don't free @p. * @p: object to reallocate memory for. * @new_size: how many bytes of memory are required. -- 1.5.4.rc3
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