This is a note to let you know that I've just added the patch titled
string.h: add array-wrappers for (v)memdup_user()
to the 5.15-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
string.h-add-array-wrappers-for-v-memdup_user.patch
and it can be found in the queue-5.15 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit e1a1b2295ab6d3c2d7874b64ba48f4cefd279822
Author: Philipp Stanner <pstanner@xxxxxxxxxx>
Date: Wed Sep 20 14:36:09 2023 +0200
string.h: add array-wrappers for (v)memdup_user()
[ Upstream commit 313ebe47d75558511aa1237b6e35c663b5c0ec6f ]
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@xxxxxxxxxx>
Signed-off-by: Philipp Stanner <pstanner@xxxxxxxxxx>
Reviewed-by: Andy Shevchenko <andy.shevchenko@xxxxxxxxx>
Reviewed-by: Kees Cook <keescook@xxxxxxxxxxxx>
Reviewed-by: Zack Rusin <zackr@xxxxxxxxxx>
Signed-off-by: Dave Airlie <airlied@xxxxxxxxxx>
Link: https://patchwork.freedesktop.org/patch/msgid/20230920123612.16914-3-pstanner@xxxxxxxxxx
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/include/linux/string.h b/include/linux/string.h
index d68097b4f600b..3b9f5abe5ee83 100644
--- a/include/linux/string.h
+++ b/include/linux/string.h
@@ -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
*/
