blob: 4c744ba2b1c654e27b561efe577d99f05d0ede02 [file] [log] [blame]
From: Al Viro <viro@zeniv.linux.org.uk>
Date: Wed, 17 Aug 2016 16:36:37 -0400
Subject: asm-generic: make copy_from_user() zero the destination properly
commit 2545e5da080b4839dd859e3b09343a884f6ab0e3 upstream.
... in all cases, including the failing access_ok()
Note that some architectures using asm-generic/uaccess.h have
__copy_from_user() not zeroing the tail on failure halfway
through. This variant works either way.
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
include/asm-generic/uaccess.h | 10 ++++++----
1 file changed, 6 insertions(+), 4 deletions(-)
--- a/include/asm-generic/uaccess.h
+++ b/include/asm-generic/uaccess.h
@@ -255,11 +255,13 @@ extern int __get_user_bad(void) __attrib
static inline long copy_from_user(void *to,
const void __user * from, unsigned long n)
{
+ unsigned long res = n;
might_fault();
- if (access_ok(VERIFY_READ, from, n))
- return __copy_from_user(to, from, n);
- else
- return n;
+ if (likely(access_ok(VERIFY_READ, from, n)))
+ res = __copy_from_user(to, from, n);
+ if (unlikely(res))
+ memset(to + (n - res), 0, res);
+ return res;
}
static inline long copy_to_user(void __user *to,