Andreas Rheinhardt: In my test case: avformat_open_input(pInputContext, ...) returns an error code
Attempts to free the (allocated?) context memory then causes a NULL reference exception when accessing &s->internal->id3v2_meta, etc. since &s->internal is NULL. avformat_free_context(pInputContext) - Robert. -----Original Message----- From: ffmpeg-devel <[email protected]> On Behalf Of Andreas Rheinhardt Sent: June 8, 2021 1:21 PM To: [email protected] Subject: Re: [FFmpeg-devel] [PATCH] Null check of &s->internal before attempting to free dict and pkt - avoid Null pointer dereference crash Robert Beyer: > --- > libavformat/utils.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/libavformat/utils.c b/libavformat/utils.c > index fe8eaa6cb3..73a7d13123 100644 > --- a/libavformat/utils.c > +++ b/libavformat/utils.c > @@ -4331,9 +4331,11 @@ void avformat_free_context(AVFormatContext *s) > } > av_freep(&s->chapters); > av_dict_free(&s->metadata); > - av_dict_free(&s->internal->id3v2_meta); > - av_packet_free(&s->internal->pkt); > - av_packet_free(&s->internal->parse_pkt); > + if (&s->internal) { > + av_dict_free(&s->internal->id3v2_meta); > + av_packet_free(&s->internal->pkt); > + av_packet_free(&s->internal->parse_pkt); > + } > av_freep(&s->streams); > flush_packet_queue(s); > av_freep(&s->internal); > 1. Checking for &s->internal is nonsense: If s is not NULL and points to an AVFormatContext, &s->internal is so, too. You want to check for s->internal. 2. avformat_alloc_context() (the only function that directly allocates AVFormatContexts) ensures that every successfully allocated AVFormatContext has an AVFormatInternal set, so the issue should just not happen. If it does happen for you, then please provide the necessary details to reproduce it. - Andreas _______________________________________________ ffmpeg-devel mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe". _______________________________________________ ffmpeg-devel mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
