[FFmpeg-devel] [libav-devel] [PATCH] avformat/flvenc: check that the codec_tag fits in one byte

[Andreas Cadhalpun]

On 01.03.2015 21:25, Luca Barbato wrote:
> On 01/03/15 21:22, Diego Biurrun wrote:
>> On Sat, Feb 28, 2015 at 09:12:57PM +0100, Andreas Cadhalpun wrote:
>>>  From 850352d0e1c262b434094fb19787bbd5b6bf6c57 Mon Sep 17 00:00:00 2001
>>> From: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
>>> Date: Sat, 28 Feb 2015 20:58:31 +0100
>>> Subject: [PATCH] avformat/flvenc: check that the codec_tag fits in one byte
>>>
>>> flags is later written with avio_w8 and if it doesn't fit in one byte it
>>> triggers an av_assert2.
>>>
>>> --- a/libavformat/flvenc.c
>>> +++ b/libavformat/flvenc.c
>>> @@ -537,7 +537,7 @@ static int flv_write_packet(AVFormatContext *s, AVPacket *pkt)
>>>           avio_w8(pb, FLV_TAG_TYPE_VIDEO);
>>>
>>>           flags = enc->codec_tag;
>>> -        if (flags == 0) {
>>> +        if (flags == 0 || flags < -128 || flags > 255) {
>>>               av_log(s, AV_LOG_ERROR,
>>>                      "Video codec '%s' is not compatible with FLV\n",
>>>                      avcodec_get_name(enc->codec_id));
>>
>> Maybe flags should be uint8_t instead?
>>
>
> No, the proper way is to blacklist/whitelist the supported codecs for flv.

It can be limited even further [1]:
-        if (flags == 0) {
+        if (flags <= 0 || flags > 15) {

Best regards,
Andreas

1: 
https://git.videolan.org/?p=ffmpeg.git;a=commitdiff;h=e8565d21c276ab9ac5ce785549420321fbd0b093