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

[Lucas Stach]

Hi Tomeu,

Am Freitag, den 19.05.2017, 12:40 +0200 schrieb 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) {

This can be simplified: If this is a indexed draw (index_size != 0) then
we will have a indexbuf at that point in the code, as its either
provided or constructed via the util_upload_index_buffer() call.

Mind if squash this simplification into your patch while pushing?

Regards,
Lucas

> +         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 = {};