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, 10 insertions, 3 deletions

diff --git a/src/gallium/drivers/softpipe/sp_draw_arrays.c b/src/gallium/drivers/softpipe/sp_draw_arrays.c
index 839fd220500..45b1390de4d 100644
--- a/src/gallium/drivers/softpipe/sp_draw_arrays.c
+++ b/src/gallium/drivers/softpipe/sp_draw_arrays.c
@@ -89,13 +89,20 @@ softpipe_draw_vbo(struct pipe_context *pipe,
 
    /* Map index buffer, if present */
    if (info->indexed) {
+      unsigned available_space = ~0;
       mapped_indices = sp->index_buffer.user_buffer;
-      if (!mapped_indices)
+      if (!mapped_indices) {
          mapped_indices = softpipe_resource(sp->index_buffer.buffer)->data;
+         if (sp->index_buffer.buffer->width0 > sp->index_buffer.offset)
+            available_space =
+               (sp->index_buffer.buffer->width0 - sp->index_buffer.offset);
+         else
+            available_space = 0;
+      }
 
       draw_set_indexes(draw,
                        (ubyte *) mapped_indices + sp->index_buffer.offset,
-                       sp->index_buffer.index_size);
+                       sp->index_buffer.index_size, available_space);
    }
 
 
@@ -125,7 +132,7 @@ softpipe_draw_vbo(struct pipe_context *pipe,
       draw_set_mapped_vertex_buffer(draw, i, NULL, 0);
    }
    if (mapped_indices) {
-      draw_set_indexes(draw, NULL, 0);
+      draw_set_indexes(draw, NULL, 0, 0);
    }
 
    draw_set_mapped_so_targets(draw, 0, NULL);