The memmap options sent to the udl framebuffer driver were not being
checked for all sets of possible crazy values.  Fix this up by properly
bounding the allowed values.

Reported-by: Eyal Itkin <eya...@checkpoint.com>
Cc: stable <sta...@vger.kernel.org>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

diff --git a/drivers/gpu/drm/udl/udl_fb.c b/drivers/gpu/drm/udl/udl_fb.c
index b5b335c9b2bb..2ebdc6d5a76e 100644
--- a/drivers/gpu/drm/udl/udl_fb.c
+++ b/drivers/gpu/drm/udl/udl_fb.c
@@ -159,10 +159,15 @@ static int udl_fb_mmap(struct fb_info *info, struct 
vm_area_struct *vma)
 {
        unsigned long start = vma->vm_start;
        unsigned long size = vma->vm_end - vma->vm_start;
-       unsigned long offset = vma->vm_pgoff << PAGE_SHIFT;
+       unsigned long offset;
        unsigned long page, pos;
 
-       if (offset + size > info->fix.smem_len)
+       if (vma->vm_pgoff > (~0UL >> PAGE_SHIFT))
+               return -EINVAL;
+
+       offset = vma->vm_pgoff << PAGE_SHIFT;
+
+       if (offset > info->fix.smem_len || size > info->fix.smem_len - offset)
                return -EINVAL;
 
        pos = (unsigned long)info->fix.smem_start + offset;
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