mp4: handle missing timescale

Avoid various divide-by-zeros when there are durations with no timescale
set. Also fix a rare potential memory leak while I'm here.

1 files changed, 20 insertions, 12 deletions

diff --git a/epan/dissectors/file-mp4.c b/epan/dissectors/file-mp4.c
index 44be681632..2725675d2c 100644
--- a/epan/dissectors/file-mp4.c
+++ b/epan/dissectors/file-mp4.c
@@ -209,13 +209,17 @@ make_fract(guint x)
 }
 
 static inline gchar *
-timescaled_val_to_str(guint64 val)
+timescaled_val_to_str(wmem_allocator_t *pool, guint64 val)
 {
     nstime_t nstime;
 
+    if (mvhd_timescale == 0) {
+        return wmem_strdup(pool, "no timescale");
+    }
+
     nstime.secs = val / mvhd_timescale;
     nstime.nsecs = (val % mvhd_timescale) * (1000000000UL / mvhd_timescale);
-    return rel_time_to_str(NULL, &nstime);
+    return rel_time_to_str(pool, &nstime);
 }
 
 static gint
@@ -283,10 +287,17 @@ dissect_mp4_mvhd_body(tvbuff_t *tvb, gint offset, gint len _U_,
     } else {
         duration = tvb_get_ntoh64(tvb , offset);
     }
-    proto_tree_add_uint64_format(tree, hf_mp4_mvhd_duration,
-            tvb, offset, time_len, duration,
-            "Duration: %f seconds (%" G_GUINT64_FORMAT ")",
-            (double) duration / mvhd_timescale, duration);
+    if (mvhd_timescale == 0) {
+        proto_tree_add_uint64_format(tree, hf_mp4_mvhd_duration,
+                tvb, offset, time_len, duration,
+                "Duration: no timescale (%" G_GUINT64_FORMAT ")",
+                duration);
+    } else {
+        proto_tree_add_uint64_format(tree, hf_mp4_mvhd_duration,
+                tvb, offset, time_len, duration,
+                "Duration: %f seconds (%" G_GUINT64_FORMAT ")",
+                (double) duration / mvhd_timescale, duration);
+    }
     offset += time_len;
 
     rate = tvb_get_ntohs(tvb, offset);
@@ -738,7 +749,7 @@ dissect_mp4_ctts_body(tvbuff_t *tvb, gint offset, gint len,
 
 static gint
 dissect_mp4_elst_body(tvbuff_t *tvb, gint offset, gint len,
-        packet_info *pinfo _U_, guint depth _U_, proto_tree *tree)
+        packet_info *pinfo, guint depth _U_, proto_tree *tree)
 {
     guint8 version;
     guint32 entry_cnt;
@@ -771,7 +782,7 @@ dissect_mp4_elst_body(tvbuff_t *tvb, gint offset, gint len,
         } else {
             segment_duration = tvb_get_ntohl(tvb, offset);
         }
-        segment_duration_str = timescaled_val_to_str(segment_duration);
+        segment_duration_str = timescaled_val_to_str(pinfo->pool, segment_duration);
         proto_tree_add_uint64_format(subtree, hf_mp4_elst_segment_duration,
                 tvb, offset, field_length, segment_duration,
                 "Segment duration: %s (%" G_GUINT64_FORMAT ")",
@@ -783,7 +794,7 @@ dissect_mp4_elst_body(tvbuff_t *tvb, gint offset, gint len,
         } else {
             media_time = tvb_get_ntohl(tvb, offset);
         }
-        media_time_str = timescaled_val_to_str(media_time);
+        media_time_str = timescaled_val_to_str(pinfo->pool, media_time);
         proto_tree_add_int64_format(subtree, hf_mp4_elst_media_time,
                 tvb, offset, field_length, media_time,
                 "Media time: %s (%" G_GINT64_FORMAT ")",
@@ -801,9 +812,6 @@ dissect_mp4_elst_body(tvbuff_t *tvb, gint offset, gint len,
         proto_item_append_text (subtree_item,
                 " Segment duration: %s; Media time: %s; Media rate: %d.%d",
                 segment_duration_str, media_time_str, rate_int, rate_fraction);
-
-        wmem_free (NULL, segment_duration_str);
-        wmem_free (NULL, media_time_str);
     }
 
     return len;