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

[ Upstream commit 313ebe47d7 ]

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: David Airlie <airlied@redhat.com>
Signed-off-by: Philipp Stanner <pstanner@redhat.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Zack Rusin <zackr@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20230920123612.16914-3-pstanner@redhat.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Philipp Stanner 2023-09-20 14:36:09 +02:00 committed by Greg Kroah-Hartman
parent 24faa2740b
commit 2fabc3289b
1 changed files with 40 additions and 0 deletions
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40
include/linux/string.h
View File

@ -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
*/