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 <[email protected]>
Reviewed-by: José Fonseca <[email protected]>
Reviewed-by: Roland Scheidegger <[email protected]>

1 files changed, 10 insertions, 4 deletions

diff --git a/src/gallium/drivers/llvmpipe/lp_draw_arrays.c b/src/gallium/drivers/llvmpipe/lp_draw_arrays.c
index 63c22c31304..4e239043ec4 100644
--- a/src/gallium/drivers/llvmpipe/lp_draw_arrays.c
+++ b/src/gallium/drivers/llvmpipe/lp_draw_arrays.c
@@ -81,13 +81,19 @@ llvmpipe_draw_vbo(struct pipe_context *pipe, const struct pipe_draw_info *info)
 
    /* Map index buffer, if present */
    if (info->indexed) {
+      unsigned available_space = ~0;
       mapped_indices = lp->index_buffer.user_buffer;
-      if (!mapped_indices)
+      if (!mapped_indices) {
          mapped_indices = llvmpipe_resource_data(lp->index_buffer.buffer);
-
+         if (lp->index_buffer.buffer->width0 > lp->index_buffer.offset)
+            available_space =
+               (lp->index_buffer.buffer->width0 - lp->index_buffer.offset);
+         else
+            available_space = 0;
+      }
       draw_set_indexes(draw,
                        (ubyte *) mapped_indices + lp->index_buffer.offset,
-                       lp->index_buffer.index_size);
+                       lp->index_buffer.index_size, available_space);
    }
 
    for (i = 0; i < lp->num_so_targets; i++) {
@@ -126,7 +132,7 @@ llvmpipe_draw_vbo(struct pipe_context *pipe, const struct pipe_draw_info *info)
       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);