[FFmpeg-cvslog] avcodec/movtextenc: Don't presume every style to have a font

[Andreas Rheinhardt]

ffmpeg | branch: master | Andreas Rheinhardt <andreas.rheinhardt at gmail.com> | Fri Oct 16 16:33:23 2020 +0200| [0dd7b8232d38317abc195edc48434ac1fd3e80fd] | committer: Andreas Rheinhardt

avcodec/movtextenc: Don't presume every style to have a font

Fixes segfaults in the absence of fonts; this can happen because the
file didn't contain any or because the allocation of the font-string
failed.

Reviewed-by: Philip Langdale <philipl at overt.org>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at gmail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=0dd7b8232d38317abc195edc48434ac1fd3e80fd
---

 libavcodec/movtextenc.c | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/libavcodec/movtextenc.c b/libavcodec/movtextenc.c
index 81e8c2e802..dcdbf16e08 100644
--- a/libavcodec/movtextenc.c
+++ b/libavcodec/movtextenc.c
@@ -298,10 +298,14 @@ static int encode_sample_description(AVCodecContext *avctx)
     // is avaiable in the ASS header
     if (style && ass->styles_count) {
         // Find unique font names
-        av_dynarray_add(&s->fonts, &s->font_count, style->font_name);
-        font_names_total_len += strlen(style->font_name);
+        if (style->font_name) {
+            av_dynarray_add(&s->fonts, &s->font_count, style->font_name);
+            font_names_total_len += strlen(style->font_name);
+        }
         for (i = 0; i < ass->styles_count; i++) {
             int found = 0;
+            if (!ass->styles[i].font_name)
+                continue;
             for (j = 0; j < s->font_count; j++) {
                 if (!strcmp(s->fonts[j], ass->styles[i].font_name)) {
                     found = 1;