From e9d408e107db9a554b36c3a79f67b37dd3e16da0 Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 24 Dec 2015 00:06:05 -0500 Subject: new helper: memdup_user_nul() Similar to memdup_user(), except that allocated buffer is one byte longer and '\0' is stored after the copied data. Signed-off-by: Al Viro --- mm/util.c | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) (limited to 'mm/util.c') diff --git a/mm/util.c b/mm/util.c index 9af1c12b310c..2d28f7930043 100644 --- a/mm/util.c +++ b/mm/util.c @@ -176,6 +176,37 @@ char *strndup_user(const char __user *s, long n) } EXPORT_SYMBOL(strndup_user); +/** + * memdup_user_nul - duplicate memory region from user space and NUL-terminate + * + * @src: source address in user space + * @len: number of bytes to copy + * + * Returns an ERR_PTR() on failure. + */ +void *memdup_user_nul(const void __user *src, size_t len) +{ + char *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 + 1, GFP_KERNEL); + if (!p) + return ERR_PTR(-ENOMEM); + + if (copy_from_user(p, src, len)) { + kfree(p); + return ERR_PTR(-EFAULT); + } + p[len] = '\0'; + + return p; +} +EXPORT_SYMBOL(memdup_user_nul); + void __vma_link_list(struct mm_struct *mm, struct vm_area_struct *vma, struct vm_area_struct *prev, struct rb_node *rb_parent) { -- cgit v1.2.3-59-g8ed1b