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Commit e9d408e1 authored by Al Viro's avatar Al Viro
Browse files

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: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 74bf8efb

include/linux/string.h

+1 −0
Original line number Diff line number Diff line
@@ -10,6 +10,7 @@ 


extern char *strndup_user(const char __user *, long);

extern void *memdup_user(const void __user *, size_t);

extern void *memdup_user_nul(const void __user *, size_t);



/*

 * Include machine specific inline routines

mm/util.c

+31 −0
Original line number Diff line number Diff line
@@ -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)

{