[FFmpeg-cvslog] ffmdec: reject zero-sized chunks

[Andreas Cadhalpun]

ffmpeg | branch: release/2.8 | Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com> | Wed Dec  2 22:47:12 2015 +0100| [76af12f5429b72820afd3b448cb38e9709993b03] | committer: Andreas Cadhalpun

ffmdec: reject zero-sized chunks

If size is zero, avio_get_str fails, leaving the buffer uninitialized.
This causes invalid reads in av_set_options_string.

Reviewed-by: Michael Niedermayer <michael at niedermayer.cc>
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
(cherry picked from commit a611375db532c3d5363d97b10fadd0211811a4fd)
Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=76af12f5429b72820afd3b448cb38e9709993b03
---

 libavformat/ffmdec.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/libavformat/ffmdec.c b/libavformat/ffmdec.c
index b743c87..7fa66ba 100644
--- a/libavformat/ffmdec.c
+++ b/libavformat/ffmdec.c
@@ -415,7 +415,7 @@ static int ffm2_read_header(AVFormatContext *s)
             }
             break;
         case MKBETAG('S', '2', 'V', 'I'):
-            if (f_stvi++) {
+            if (f_stvi++ || !size) {
                 ret = AVERROR(EINVAL);
                 goto fail;
             }
@@ -430,7 +430,7 @@ static int ffm2_read_header(AVFormatContext *s)
                 goto fail;
             break;
         case MKBETAG('S', '2', 'A', 'U'):
-            if (f_stau++) {
+            if (f_stau++ || !size) {
                 ret = AVERROR(EINVAL);
                 goto fail;
             }