uaccess: Fix is_source param for check_copy_size() in copy_to_iter_mc…

…safe()

copy_to_iter_mcsafe() is passing in the is_source parameter as "false"
to check_copy_size(). This is different than what copy_to_iter() does.
Also, the addr parameter passed to check_copy_size() is the source so
therefore we should be passing in "true" instead.

Fixes: 8780356 ("x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()")
Cc: <[email protected]>
Reported-by: Fan Du <[email protected]>
Signed-off-by: Dave Jiang <[email protected]>
Reviewed-by: Vishal Verma <[email protected]>
Reported-by: Wenwei Tao <[email protected]>
Signed-off-by: Dan Williams <[email protected]>

include/linux/uio.h

@@ -172,7 +172,7 @@ size_t copy_from_iter_flushcache(void *addr, size_t bytes, struct iov_iter *i)
 static __always_inline __must_check
 size_t copy_to_iter_mcsafe(void *addr, size_t bytes, struct iov_iter *i)
 {
-	if (unlikely(!check_copy_size(addr, bytes, false)))
+	if (unlikely(!check_copy_size(addr, bytes, true)))
 		return 0;
 	else
 		return _copy_to_iter_mcsafe(addr, bytes, i);