diff options
| -rw-r--r-- | include/linux/string.h | 1 | ||||
| -rw-r--r-- | mm/util.c | 30 |
2 files changed, 31 insertions, 0 deletions
diff --git a/include/linux/string.h b/include/linux/string.h index d18fc198aa2f..8852739f36df 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); /* * Include machine specific inline routines 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) 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. |