[PATCH] etnaviv: Don't try to use the index buffer if size is zero

[Tomeu Vizoso]

If info->index_size is zero, info->index will point to uninitialized
memory.

Fatal signal 11 (SIGSEGV), code 2, fault addr 0xab5d07a3 in tid 20456 (surfaceflinger)

Signed-off-by: Tomeu Vizoso <tomeu.vizoso at collabora.com>
Cc: etnaviv at lists.freedesktop.org
Cc: Marek Olšák <marek.olsak at amd.com>
Fixes: 330d0607ed60 ("gallium: remove pipe_index_buffer and set_index_buffer")
---
 src/gallium/drivers/etnaviv/etnaviv_context.c | 36 +++++++++++++++------------
 1 file changed, 20 insertions(+), 16 deletions(-)

diff --git a/src/gallium/drivers/etnaviv/etnaviv_context.c b/src/gallium/drivers/etnaviv/etnaviv_context.c
index 306cb6fc498d..dcda4088bfd5 100644
--- a/src/gallium/drivers/etnaviv/etnaviv_context.c
+++ b/src/gallium/drivers/etnaviv/etnaviv_context.c
@@ -178,24 +178,28 @@ etna_draw_vbo(struct pipe_context *pctx, const struct pipe_draw_info *info)
 
    /* Upload a user index buffer. */
    unsigned index_offset = 0;
-   struct pipe_resource *indexbuf = info->has_user_indices ? NULL : info->index.resource;
-   if (info->index_size && info->has_user_indices &&
-       !util_upload_index_buffer(pctx, info, &indexbuf, &index_offset)) {
-      BUG("Index buffer upload failed.");
-      return;
-   }
+   struct pipe_resource *indexbuf = NULL;
 
-   if (info->index_size && indexbuf) {
-      ctx->index_buffer.FE_INDEX_STREAM_BASE_ADDR.bo = etna_resource(indexbuf)->bo;
-      ctx->index_buffer.FE_INDEX_STREAM_BASE_ADDR.offset = index_offset;
-      ctx->index_buffer.FE_INDEX_STREAM_BASE_ADDR.flags = ETNA_RELOC_READ;
-      ctx->index_buffer.FE_INDEX_STREAM_CONTROL = translate_index_size(info->index_size);
-      ctx->dirty |= ETNA_DIRTY_INDEX_BUFFER;
-   }
+   if (info->index_size) {
+      indexbuf = info->has_user_indices ? NULL : info->index.resource;
+      if (info->has_user_indices &&
+          !util_upload_index_buffer(pctx, info, &indexbuf, &index_offset)) {
+         BUG("Index buffer upload failed.");
+         return;
+      }
 
-   if (info->index_size && !ctx->index_buffer.FE_INDEX_STREAM_BASE_ADDR.bo) {
-      BUG("Unsupported or no index buffer");
-      return;
+      if (indexbuf) {
+         ctx->index_buffer.FE_INDEX_STREAM_BASE_ADDR.bo = etna_resource(indexbuf)->bo;
+         ctx->index_buffer.FE_INDEX_STREAM_BASE_ADDR.offset = index_offset;
+         ctx->index_buffer.FE_INDEX_STREAM_BASE_ADDR.flags = ETNA_RELOC_READ;
+         ctx->index_buffer.FE_INDEX_STREAM_CONTROL = translate_index_size(info->index_size);
+         ctx->dirty |= ETNA_DIRTY_INDEX_BUFFER;
+      }
+
+      if (!ctx->index_buffer.FE_INDEX_STREAM_BASE_ADDR.bo) {
+         BUG("Unsupported or no index buffer");
+         return;
+      }
    }
 
    struct etna_shader_key key = {};
-- 
2.9.3