Messages in this thread Patch in this message | | | Date | Fri, 06 Mar 2009 15:04:12 +0800 | From | Li Zefan <> | Subject | [RFC][PATCH] kmemdup_from_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 }
kmemdup_from_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.
A qucik grep shows 250+ places where kmemdup_from_user() *may* be used. I'll prepare a patchset to do this conversion.
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> --- include/linux/string.h | 1 + mm/util.c | 24 ++++++++++++++++++++++++ 2 files changed, 25 insertions(+), 0 deletions(-)
diff --git a/include/linux/string.h b/include/linux/string.h index 76ec218..397e622 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -105,6 +105,7 @@ extern void * memchr(const void *,int,__kernel_size_t); extern char *kstrdup(const char *s, gfp_t gfp); extern char *kstrndup(const char *s, size_t len, gfp_t gfp); extern void *kmemdup(const void *src, size_t len, gfp_t gfp); +extern void *kmemdup_from_user(const void __user *src, size_t len, gfp_t gfp); extern char **argv_split(gfp_t gfp, const char *str, int *argcp); extern void argv_free(char **argv); diff --git a/mm/util.c b/mm/util.c index 37eaccd..a608ebb 100644 --- a/mm/util.c +++ b/mm/util.c @@ -70,6 +70,30 @@ void *kmemdup(const void *src, size_t len, gfp_t gfp) EXPORT_SYMBOL(kmemdup); /** + * kmemdup_from_user - duplicate memory region from user space + * + * @src: source address in user space + * @len: number of bytes to copy + * @gfp: GFP mask to use + */ +void *kmemdup_from_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(kmemdup_from_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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