draw: try to prevent overflows on index buffers

Pass in the size of the index buffer, when available, and use it
to handle out of bounds conditions. The behavior in the case of
an overflow needs to be the same as with other overflows in the
vertex processing pipeline meaning that a vertex should still
be generated but all attributes in it set to zero.

Signed-off-by: Zack Rusin <zackr@vmware.com>
Reviewed-by: José Fonseca <jfonseca@vmware.com>
Reviewed-by: Roland Scheidegger <sroland@vmware.com>

1 files changed, 6 insertions, 1 deletions

diff --git a/src/gallium/auxiliary/draw/draw_context.c b/src/gallium/auxiliary/draw/draw_context.c
index 4eb1919b87..78190388ef 100644
--- a/src/gallium/auxiliary/draw/draw_context.c
+++ b/src/gallium/auxiliary/draw/draw_context.c
@@ -627,7 +627,8 @@ void draw_set_render( struct draw_context *draw,
  */
 void
 draw_set_indexes(struct draw_context *draw,
-                 const void *elements, unsigned elem_size)
+                 const void *elements, unsigned elem_size,
+                 unsigned elem_buffer_space)
 {
    assert(elem_size == 0 ||
           elem_size == 1 ||
@@ -635,6 +636,10 @@ draw_set_indexes(struct draw_context *draw,
           elem_size == 4);
    draw->pt.user.elts = elements;
    draw->pt.user.eltSizeIB = elem_size;
+   if (elem_size)
+      draw->pt.user.eltMax = elem_buffer_space / elem_size;
+   else
+      draw->pt.user.eltMax = 0;
 }