media: rkvdec: Improve handling missing short/long term RPS

The values of ext_sps_st_rps and ext_sps_lt_rps in struct rkvdec_hevc_run
are not initialized when the respective controls are not set by userspace.

When this is the case, set them to NULL so the rkvdec_hevc_run_preamble
function that parses controls does not access garbage data which leads to
a panic on unaccessible memory.

Fixes: c9a59dc ("media: rkvdec: Add HEVC support for the VDPU381 variant")
Reported-by: Christian Hewitt <[email protected]>
Suggested-by: Jonas Karlman <[email protected]>
Signed-off-by: Detlev Casanova <[email protected]>
Tested-by: Christian Hewitt <[email protected]>
Reviewed-by: Nicolas Dufresne <[email protected]>
Signed-off-by: Nicolas Dufresne <[email protected]>
Signed-off-by: Mauro Carvalho Chehab <[email protected]>

Author: cazou

drivers/media/platform/rockchip/rkvdec/rkvdec-hevc-common.c

@@ -500,11 +500,15 @@ void rkvdec_hevc_run_preamble(struct rkvdec_ctx *ctx,
 		ctrl = v4l2_ctrl_find(&ctx->ctrl_hdl,
 				      V4L2_CID_STATELESS_HEVC_EXT_SPS_ST_RPS);
 		run->ext_sps_st_rps = ctrl ? ctrl->p_cur.p : NULL;
+	} else {
+		run->ext_sps_st_rps = NULL;
 	}
 	if (ctx->has_sps_lt_rps) {
 		ctrl = v4l2_ctrl_find(&ctx->ctrl_hdl,
 				      V4L2_CID_STATELESS_HEVC_EXT_SPS_LT_RPS);
 		run->ext_sps_lt_rps = ctrl ? ctrl->p_cur.p : NULL;
+	} else {
+		run->ext_sps_lt_rps = NULL;
 	}
 
 	rkvdec_run_preamble(ctx, &run->base);