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

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

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

commit acb2505d0119033a80c85ac8d02dccae41271667 upstream.

... that should zero on faults.  Also remove the <censored> helpful
logics wrt range truncation copied from ppc32.  Where it had ever
been needed only in case of copy_from_user() *and* had not been merged
into the mainline until a month after the need had disappeared.
A decade before openrisc went into mainline, I might add...

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

---
 arch/openrisc/include/asm/uaccess.h |   33 ++++++++++-----------------------
 1 file changed, 10 insertions(+), 23 deletions(-)

--- a/arch/openrisc/include/asm/uaccess.h
+++ b/arch/openrisc/include/asm/uaccess.h
@@ -273,28 +273,20 @@ __copy_tofrom_user(void *to, const void
 static inline unsigned long
 copy_from_user(void *to, const void *from, unsigned long n)
 {
-       unsigned long over;
+       unsigned long res = n;
 
-       if (access_ok(VERIFY_READ, from, n))
-               return __copy_tofrom_user(to, from, n);
-       if ((unsigned long)from < TASK_SIZE) {
-               over = (unsigned long)from + n - TASK_SIZE;
-               return __copy_tofrom_user(to, from, n - over) + over;
-       }
-       return n;
+       if (likely(access_ok(VERIFY_READ, from, n)))
+               n = __copy_tofrom_user(to, from, n);
+       if (unlikely(res))
+               memset(to + (n - res), 0, res);
+       return res;
 }
 
 static inline unsigned long
 copy_to_user(void *to, const void *from, unsigned long n)
 {
-       unsigned long over;
-
-       if (access_ok(VERIFY_WRITE, to, n))
-               return __copy_tofrom_user(to, from, n);
-       if ((unsigned long)to < TASK_SIZE) {
-               over = (unsigned long)to + n - TASK_SIZE;
-               return __copy_tofrom_user(to, from, n - over) + over;
-       }
+       if (likely(access_ok(VERIFY_WRITE, to, n)))
+               n = __copy_tofrom_user(to, from, n);
        return n;
 }
 
@@ -303,13 +295,8 @@ extern unsigned long __clear_user(void *
 static inline __must_check unsigned long
 clear_user(void *addr, unsigned long size)
 {
-
-       if (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;
-       }
+       if (likely(access_ok(VERIFY_WRITE, addr, size)))
+               size = __clear_user(addr, size);
        return size;
 }
 


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