From: Philipp Stanner pstanner@redhat.com

commit 313ebe47d75558511aa1237b6e35c663b5c0ec6f upstream.

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-pstanne... [ fp: fix small conflict in header includes; take linux/errno.h as well ] Signed-off-by: Fedor Pchelkin pchelkin@ispras.ru ---

s390 and x86_64 allmodconfig build passed.

include/linux/string.h | 41 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 41 insertions(+)

diff --git a/include/linux/string.h b/include/linux/string.h index 0cef345a6e87..cd8c007ad3be 100644 --- a/include/linux/string.h +++ b/include/linux/string.h @@ -5,6 +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 <stdarg.h> #include <uapi/linux/string.h>

@@ -13,6 +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 */