[VIDEO] sbuslib: Disallow private mmaps.

The COW semantics just do not make any sense especially
with the physically discontiguous I/O mappings possible
here.

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/video/sbuslib.c b/drivers/video/sbuslib.c
index 646c43f921c..3a74a63dd4f 100644
--- a/drivers/video/sbuslib.c
+++ b/drivers/video/sbuslib.c
@@ -46,6 +46,9 @@ int sbusfb_mmap_helper(struct sbus_mmap_map *map,
         unsigned long off;
         int i;
                                         
+        if (!(vma->vm_flags & (VM_SHARED | VM_MAYSHARE)))
+                return -EINVAL;
+
         size = vma->vm_end - vma->vm_start;
         if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT))
                 return -EINVAL;