media: cedrus: Fix NULL buf dereference

This is a regression introduced after porting to vb2_find_buffer.
The function returnis NULL when the buffer isn't found. The HEVC
decoder would call a helper to get the motion vector buffer address
by passing the index. This is fixed by passing the buffer
pointer instead of the index.

Fixes: 7f361451 ("cedrus: Use vb2_find_buffer")
Signed-off-by: Nicolas Dufresne <nicolas.dufresne@collabora.com>

drivers/staging/media/sunxi/cedrus/cedrus_h265.c

@@ -91,16 +91,13 @@ static void cedrus_h265_sram_write_data(struct cedrus_dev *dev, void *data,
 
 static inline dma_addr_t
 cedrus_h265_frame_info_mv_col_buf_addr(struct cedrus_ctx *ctx,
-				       unsigned int index,
+				       struct vb2_buffer *buf,
 				       const struct v4l2_ctrl_hevc_sps *sps)
 {
 	struct cedrus_buffer *cedrus_buf = NULL;
-	struct vb2_buffer *buf = NULL;
 	struct vb2_queue *vq;
 
 	vq = v4l2_m2m_get_vq(ctx->fh.m2m_ctx, V4L2_BUF_TYPE_VIDEO_CAPTURE);
-	if (vq)
-		buf = vb2_get_buffer(vq, index);
 
 	if (buf)
 		cedrus_buf = vb2_to_cedrus_buffer(buf);
@@ -148,8 +145,8 @@ static void cedrus_h265_frame_info_write_single(struct cedrus_ctx *ctx,
 	dma_addr_t dst_luma_addr = cedrus_dst_buf_addr(ctx, buf, 0);
 	dma_addr_t dst_chroma_addr = cedrus_dst_buf_addr(ctx, buf, 1);
 	dma_addr_t mv_col_buf_addr[2] = {
-		cedrus_h265_frame_info_mv_col_buf_addr(ctx, buf->index, sps),
-		cedrus_h265_frame_info_mv_col_buf_addr(ctx, buf->index, sps)
+		cedrus_h265_frame_info_mv_col_buf_addr(ctx, buf, sps),
+		cedrus_h265_frame_info_mv_col_buf_addr(ctx, buf, sps)
 	};
 	u32 offset = VE_DEC_H265_SRAM_OFFSET_FRAME_INFO +
 		     VE_DEC_H265_SRAM_OFFSET_FRAME_INFO_UNIT * index;