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-rw-r--r--mm/util.c30
1 files changed, 30 insertions, 0 deletions
diff --git a/mm/util.c b/mm/util.c
index 37eaccdf3054..7c122e49f769 100644
--- a/mm/util.c
+++ b/mm/util.c
@@ -70,6 +70,36 @@ void *kmemdup(const void *src, size_t len, gfp_t gfp)
70EXPORT_SYMBOL(kmemdup); 70EXPORT_SYMBOL(kmemdup);
71 71
72/** 72/**
73 * memdup_user - duplicate memory region from user space
74 *
75 * @src: source address in user space
76 * @len: number of bytes to copy
77 *
78 * Returns an ERR_PTR() on failure.
79 */
80void *memdup_user(const void __user *src, size_t len)
81{
82 void *p;
83
84 /*
85 * Always use GFP_KERNEL, since copy_from_user() can sleep and
86 * cause pagefault, which makes it pointless to use GFP_NOFS
87 * or GFP_ATOMIC.
88 */
89 p = kmalloc_track_caller(len, GFP_KERNEL);
90 if (!p)
91 return ERR_PTR(-ENOMEM);
92
93 if (copy_from_user(p, src, len)) {
94 kfree(p);
95 return ERR_PTR(-EFAULT);
96 }
97
98 return p;
99}
100EXPORT_SYMBOL(memdup_user);
101
102/**
73 * __krealloc - like krealloc() but don't free @p. 103 * __krealloc - like krealloc() but don't free @p.
74 * @p: object to reallocate memory for. 104 * @p: object to reallocate memory for.
75 * @new_size: how many bytes of memory are required. 105 * @new_size: how many bytes of memory are required.