[FFmpeg-cvslog] avformat/dashdec: Avoid segfault when URL template is unexpectedly missing

[sfan5]

ffmpeg | branch: master | sfan5 <sfan5 at live.de> | Thu Feb  4 09:33:17 2021 +0800| [a44c42dc31333968650382a640480cedc3c9ae3c] | committer: Steven Liu

avformat/dashdec: Avoid segfault when URL template is unexpectedly missing

This isn't supposed to happen, but unfinished support for non-templated
manifests and lack of e.g. presentationTimeOffset handling can provoke
such a situation even with well-formed input.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=a44c42dc31333968650382a640480cedc3c9ae3c
---

 libavformat/dashdec.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/libavformat/dashdec.c b/libavformat/dashdec.c
index 04dbdb668e..b82805c9ce 100644
--- a/libavformat/dashdec.c
+++ b/libavformat/dashdec.c
@@ -1626,8 +1626,15 @@ static struct fragment *get_current_fragment(struct representation *pls)
         }
     }
     if (seg) {
-        char *tmpfilename= av_mallocz(c->max_url_size);
+        char *tmpfilename;
+        if (!pls->url_template) {
+            av_log(pls->parent, AV_LOG_ERROR, "Cannot get fragment, missing template URL\n");
+            av_free(seg);
+            return NULL;
+        }
+        tmpfilename = av_mallocz(c->max_url_size);
         if (!tmpfilename) {
+            av_free(seg);
             return NULL;
         }
         ff_dash_fill_tmpl_params(tmpfilename, c->max_url_size, pls->url_template, 0, pls->cur_seq_no, 0, get_segment_start_time_based_on_timeline(pls, pls->cur_seq_no));
@@ -1638,6 +1645,7 @@ static struct fragment *get_current_fragment(struct representation *pls)
             if (!seg->url) {
                 av_log(pls->parent, AV_LOG_ERROR, "Cannot resolve template url '%s'\n", pls->url_template);
                 av_free(tmpfilename);
+                av_free(seg);
                 return NULL;
             }
         }