[FFmpeg-devel] [PATCH] avcodec/dxva2: d3d11va: don't try to get surface description for nullptr

[Anton Fedchin]

From: Anton Fedchin <afedchin at ruswizards.com>

after 153b36f there is a possibility to crash when trying to get index of
a surface which points to nirvana. it may occurs when a stream starts with
non i-frame.
---
 libavcodec/dxva2.c | 10 ++++++----
 1 file changed, 6 insertions(+), 4 deletions(-)

diff --git a/libavcodec/dxva2.c b/libavcodec/dxva2.c
index 32416112bf..dfae500444 100644
--- a/libavcodec/dxva2.c
+++ b/libavcodec/dxva2.c
@@ -771,16 +771,18 @@ unsigned ff_dxva2_get_surface_index(const AVCodecContext *avctx,
 #if CONFIG_D3D11VA
     if (avctx->pix_fmt == AV_PIX_FMT_D3D11)
         return (intptr_t)frame->data[1];
-    if (avctx->pix_fmt == AV_PIX_FMT_D3D11VA_VLD) {
+    if (avctx->pix_fmt == AV_PIX_FMT_D3D11VA_VLD && surface) {
         D3D11_VIDEO_DECODER_OUTPUT_VIEW_DESC viewDesc;
         ID3D11VideoDecoderOutputView_GetDesc((ID3D11VideoDecoderOutputView*) surface, &viewDesc);
         return viewDesc.Texture2D.ArraySlice;
     }
 #endif
 #if CONFIG_DXVA2
-    for (i = 0; i < DXVA_CONTEXT_COUNT(avctx, ctx); i++) {
-        if (avctx->pix_fmt == AV_PIX_FMT_DXVA2_VLD && ctx->dxva2.surface[i] == surface)
-            return i;
+    if (avctx->pix_fmt == AV_PIX_FMT_DXVA2_VLD) {
+        for (i = 0; i < DXVA_CONTEXT_COUNT(avctx, ctx); i++) {
+            if (ctx->dxva2.surface[i] == surface)
+                return i;
+        }
     }
 #endif
 
-- 
2.17.1.windows.2