From d98dfcecad179260182d90ed1d170c1037db7568 Mon Sep 17 00:00:00 2001 From: Andreas Rheinhardt Date: Sat, 7 Oct 2023 01:07:47 +0200 Subject: [PATCH] fftools/ffmpeg_demux: Don't use fake object with av_opt_eval The av_opt_eval family of functions emits errors messages on error and can therefore not be used with fake objects when the AVClass has a custom item_name callback. The AVClass for AVCodecContext has such a custom callback (it searches whether an AVCodec is set to use its name). In practice it means that whatever is directly after the "cc" pointer to the AVClass for AVCodec in the stack frame of ist_add() will be treated as a pointer to an AVCodec with unpredictable consequences. Fix this by using an actual AVCodecContext instead of a fake object. Reviewed-by: Anton Khirnov Signed-off-by: Andreas Rheinhardt --- fftools/ffmpeg_demux.c | 15 +++++++-------- 1 file changed, 7 insertions(+), 8 deletions(-) diff --git a/fftools/ffmpeg_demux.c b/fftools/ffmpeg_demux.c index c71edf01a5..41fcb678c6 100644 --- a/fftools/ffmpeg_demux.c +++ b/fftools/ffmpeg_demux.c @@ -1042,9 +1042,6 @@ static int ist_add(const OptionsContext *o, Demuxer *d, AVStream *st) char *codec_tag = NULL; char *next; char *discard_str = NULL; - const AVClass *cc = avcodec_get_class(); - const AVOption *discard_opt = av_opt_find(&cc, "skip_frame", NULL, - 0, AV_OPT_SEARCH_FAKE_OBJ); int ret; ds = demux_stream_alloc(d, st); @@ -1176,18 +1173,20 @@ static int ist_add(const OptionsContext *o, Demuxer *d, AVStream *st) (o->data_disable && ist->st->codecpar->codec_type == AVMEDIA_TYPE_DATA)) ist->user_set_discard = AVDISCARD_ALL; + ist->dec_ctx = avcodec_alloc_context3(ist->dec); + if (!ist->dec_ctx) + return AVERROR(ENOMEM); + if (discard_str) { - ret = av_opt_eval_int(&cc, discard_opt, discard_str, &ist->user_set_discard); + const AVOption *discard_opt = av_opt_find(ist->dec_ctx, "skip_frame", + NULL, 0, 0); + ret = av_opt_eval_int(ist->dec_ctx, discard_opt, discard_str, &ist->user_set_discard); if (ret < 0) { av_log(ist, AV_LOG_ERROR, "Error parsing discard %s.\n", discard_str); return ret; } } - ist->dec_ctx = avcodec_alloc_context3(ist->dec); - if (!ist->dec_ctx) - return AVERROR(ENOMEM); - ret = avcodec_parameters_to_context(ist->dec_ctx, par); if (ret < 0) { av_log(ist, AV_LOG_ERROR, "Error initializing the decoder context.\n");