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authorLi Zefan <lizf@cn.fujitsu.com>2009-03-31 15:23:16 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2009-04-01 08:59:13 -0700
commit610a77e04a8d9fe8764dc484e2182fa251ce1cc2 (patch)
treeec55b9b3698321c3e85cd649fa927554027c75d0 /mm/util.c
parente2f17d9459aeccf4e013e31cbd741d6b1858eec4 (diff)
downloadlinux-610a77e04a8d9fe8764dc484e2182fa251ce1cc2.tar.gz
memdup_user(): introduce
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>
Diffstat (limited to 'mm/util.c')
-rw-r--r--mm/util.c30
1 files changed, 30 insertions, 0 deletions
diff --git a/mm/util.c b/mm/util.c
index 37eaccdf305..7c122e49f76 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -70,6 +70,36 @@ 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
+ *
+ * Returns an ERR_PTR() on failure.
+ */
+void *memdup_user(const void __user *src, size_t len)
+{
+ void *p;
+
+ /*
+ * Always use GFP_KERNEL, since copy_from_user() can sleep and
+ * cause pagefault, which makes it pointless to use GFP_NOFS
+ * or GFP_ATOMIC.
+ */
+ p = kmalloc_track_caller(len, GFP_KERNEL);
+ 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.