avcodec/hevcdec: further constrain some slice header field values

num_ref_idx_l0_active_minus1, num_ref_idx_l1_active_minus1,
num_ref_idx_l0_default_active_minus1, and num_ref_idx_l1_default_active_minus1
are all in the range 0 to 14, inclusive.

Signed-off-by: James Almer <jamrial@gmail.com>

libavcodec/hevc_ps.c

@@ -1762,8 +1762,14 @@ int ff_hevc_decode_nal_pps(GetBitContext *gb, AVCodecContext *avctx,
 
     pps->cabac_init_present_flag = get_bits1(gb);
 
-    pps->num_ref_idx_l0_default_active = get_ue_golomb_long(gb) + 1;
-    pps->num_ref_idx_l1_default_active = get_ue_golomb_long(gb) + 1;
+    pps->num_ref_idx_l0_default_active = get_ue_golomb_31(gb) + 1;
+    pps->num_ref_idx_l1_default_active = get_ue_golomb_31(gb) + 1;
+    if (pps->num_ref_idx_l0_default_active >= HEVC_MAX_REFS ||
+        pps->num_ref_idx_l1_default_active >= HEVC_MAX_REFS) {
+        av_log(avctx, AV_LOG_ERROR, "Too many default refs in PPS: %d/%d.\n",
+               pps->num_ref_idx_l0_default_active, pps->num_ref_idx_l1_default_active);
+        goto err;
+    }
 
     pps->pic_init_qp_minus26 = get_se_golomb(gb);
 

libavcodec/hevcdec.c

@@ -773,11 +773,11 @@ static int hls_slice_header(HEVCContext *s)
                 sh->nb_refs[L1] = s->ps.pps->num_ref_idx_l1_default_active;
 
             if (get_bits1(gb)) { // num_ref_idx_active_override_flag
-                sh->nb_refs[L0] = get_ue_golomb_long(gb) + 1;
+                sh->nb_refs[L0] = get_ue_golomb_31(gb) + 1;
                 if (sh->slice_type == HEVC_SLICE_B)
-                    sh->nb_refs[L1] = get_ue_golomb_long(gb) + 1;
+                    sh->nb_refs[L1] = get_ue_golomb_31(gb) + 1;
             }
-            if (sh->nb_refs[L0] > HEVC_MAX_REFS || sh->nb_refs[L1] > HEVC_MAX_REFS) {
+            if (sh->nb_refs[L0] >= HEVC_MAX_REFS || sh->nb_refs[L1] >= HEVC_MAX_REFS) {
                 av_log(s->avctx, AV_LOG_ERROR, "Too many refs: %d/%d.\n",
                        sh->nb_refs[L0], sh->nb_refs[L1]);
                 return AVERROR_INVALIDDATA;