mesa/pbo: Handle zero width, height or depth when validating access

It's legal to call glTexSubImage with zero values for the width,
height or depth. Previously this was breaking the PBO access
validation because it tries to work out the last pixel accessed by
getting the pixel at height-1 and depth-1 which would end up with
bogus values.

This was causing GL errors to be generated during the Piglit
texsubimage test, although the test was passing anyway.

v2: Also check for width == 0. Don't validate the start pointer if any
    of the dimensions are zero.
Reviewed-by: Ilia Mirkin <[email protected]>

1 files changed, 6 insertions, 0 deletions

diff --git a/src/mesa/main/pbo.c b/src/mesa/main/pbo.c
index 0c160253201..7762324a4ae 100644
--- a/src/mesa/main/pbo.c
+++ b/src/mesa/main/pbo.c
@@ -103,6 +103,12 @@ _mesa_validate_pbo_access(GLuint dimensions,
       /* no buffer! */
       return GL_FALSE;
 
+   /* If the size of the image is zero then no pixels are accessed so we
+    * don't need to check anything else.
+    */
+   if (width == 0 || height == 0 || depth == 0)
+      return GL_TRUE;
+
    /* get the offset to the first pixel we'll read/write */
    start = _mesa_image_offset(dimensions, pack, width, height,
                               format, type, 0, 0, 0);