4.7-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Al Viro <v...@zeniv.linux.org.uk>

commit 224264657b8b228f949b42346e09ed8c90136a8e upstream.

should clear on access_ok() failures.  Also remove the useless
range truncation logics.

Signed-off-by: Al Viro <v...@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 arch/powerpc/include/asm/uaccess.h |   21 ++-------------------
 1 file changed, 2 insertions(+), 19 deletions(-)

--- a/arch/powerpc/include/asm/uaccess.h
+++ b/arch/powerpc/include/asm/uaccess.h
@@ -308,30 +308,17 @@ extern unsigned long __copy_tofrom_user(
 static inline unsigned long copy_from_user(void *to,
                const void __user *from, unsigned long n)
 {
-       unsigned long over;
-
-       if (access_ok(VERIFY_READ, from, n))
+       if (likely(access_ok(VERIFY_READ, from, n)))
                return __copy_tofrom_user((__force void __user *)to, from, n);
-       if ((unsigned long)from < TASK_SIZE) {
-               over = (unsigned long)from + n - TASK_SIZE;
-               return __copy_tofrom_user((__force void __user *)to, from,
-                               n - over) + over;
-       }
++      memset(to, 0, n);
        return n;
 }
 
 static inline unsigned long copy_to_user(void __user *to,
                const void *from, unsigned long n)
 {
-       unsigned long over;
-
        if (access_ok(VERIFY_WRITE, to, n))
                return __copy_tofrom_user(to, (__force void __user *)from, n);
-       if ((unsigned long)to < TASK_SIZE) {
-               over = (unsigned long)to + n - TASK_SIZE;
-               return __copy_tofrom_user(to, (__force void __user *)from,
-                               n - over) + over;
-       }
        return n;
 }
 
@@ -422,10 +409,6 @@ static inline unsigned long clear_user(v
        might_fault();
        if (likely(access_ok(VERIFY_WRITE, addr, size)))
                return __clear_user(addr, size);
-       if ((unsigned long)addr < TASK_SIZE) {
-               unsigned long over = (unsigned long)addr + size - TASK_SIZE;
-               return __clear_user(addr, size - over) + over;
-       }
        return size;
 }
 


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