Commit 313ebe47 authored by Philipp Stanner's avatar Philipp Stanner Committed by Dave Airlie
Browse files

string.h: add array-wrappers for (v)memdup_user() 



Currently, user array duplications are sometimes done without an
overflow check. Sometimes the checks are done manually; sometimes the
array size is calculated with array_size() and sometimes by calculating
n * size directly in code.

Introduce wrappers for arrays for memdup_user() and vmemdup_user() to
provide a standardized and safe way for duplicating user arrays.

This is both for new code as well as replacing usage of (v)memdup_user()
in existing code that uses, e.g., n * size to calculate array sizes.

Suggested-by: default avatarDavid Airlie <airlied@redhat.com>
Signed-off-by: default avatarPhilipp Stanner <pstanner@redhat.com>
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Reviewed-by: default avatarZack Rusin <zackr@vmware.com>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230920123612.16914-3-pstanner@redhat.com
parent 94f6f055

include/linux/string.h

+40 −0
Original line number Diff line number Diff line
@@ -5,7 +5,9 @@ 
#include <linux/compiler.h>	/* for inline */

#include <linux/types.h>	/* for size_t */

#include <linux/stddef.h>	/* for NULL */

#include <linux/err.h>		/* for ERR_PTR() */

#include <linux/errno.h>	/* for E2BIG */

#include <linux/overflow.h>	/* for check_mul_overflow() */

#include <linux/stdarg.h>

#include <uapi/linux/string.h>
@@ -14,6 +16,44 @@ extern void *memdup_user(const void __user *, size_t); 
extern void *vmemdup_user(const void __user *, size_t);

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



/**

 * memdup_array_user - duplicate array from user space

 * @src: source address in user space

 * @n: number of array members to copy

 * @size: size of one array member

 *

 * Return: an ERR_PTR() on failure. Result is physically

 * contiguous, to be freed by kfree().

 */

static inline void *memdup_array_user(const void __user *src, size_t n, size_t size)

{

	size_t nbytes;



	if (check_mul_overflow(n, size, &nbytes))

		return ERR_PTR(-EOVERFLOW);



	return memdup_user(src, nbytes);

}



/**

 * vmemdup_array_user - duplicate array from user space

 * @src: source address in user space

 * @n: number of array members to copy

 * @size: size of one array member

 *

 * Return: an ERR_PTR() on failure. Result may be not

 * physically contiguous. Use kvfree() to free.

 */

static inline void *vmemdup_array_user(const void __user *src, size_t n, size_t size)

{

	size_t nbytes;



	if (check_mul_overflow(n, size, &nbytes))

		return ERR_PTR(-EOVERFLOW);



	return vmemdup_user(src, nbytes);

}



/*

 * Include machine specific inline routines

 */