[PATCH 4.4 101/118] frv: fix clear_user()
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: 2016-09-22 17:37:55
Also in:
lkml
4.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro <viro@zeniv.linux.org.uk> commit 3b8767a8f00cc6538ba6b1cf0f88502e2fd2eb90 upstream. It should check access_ok(). Otherwise a bunch of places turn into trivially exploitable rootholes. Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- arch/frv/include/asm/uaccess.h | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-)
--- a/arch/frv/include/asm/uaccess.h
+++ b/arch/frv/include/asm/uaccess.h@@ -263,19 +263,25 @@ do { \ extern long __memset_user(void *dst, unsigned long count); extern long __memcpy_user(void *dst, const void *src, unsigned long count); -#define clear_user(dst,count) __memset_user(____force(dst), (count)) +#define __clear_user(dst,count) __memset_user(____force(dst), (count)) #define __copy_from_user_inatomic(to, from, n) __memcpy_user((to), ____force(from), (n)) #define __copy_to_user_inatomic(to, from, n) __memcpy_user(____force(to), (from), (n)) #else -#define clear_user(dst,count) (memset(____force(dst), 0, (count)), 0) +#define __clear_user(dst,count) (memset(____force(dst), 0, (count)), 0) #define __copy_from_user_inatomic(to, from, n) (memcpy((to), ____force(from), (n)), 0) #define __copy_to_user_inatomic(to, from, n) (memcpy(____force(to), (from), (n)), 0) #endif -#define __clear_user clear_user +static inline unsigned long __must_check +clear_user(void __user *to, unsigned long n) +{ + if (likely(__access_ok(to, n))) + n = __clear_user(to, n); + return n; +} static inline unsigned long __must_check __copy_to_user(void __user *to, const void *from, unsigned long n)