On Sat, 09. May 13:35, Andriy Gelman wrote: > From: Andriy Gelman <andriy.gel...@gmail.com> > > v4l2_receive_frame() uses two packets s->buf_pkt and avpkt. If avpkt > cannot be enqueued, the packet is buffered in s->buf_pkt and enqueued in > the next call. Currently the ownership transfer between the two packets > is not properly handled. A double free occurs if > ff_v4l2_context_enqueue_packet() returns EAGAIN and v4l2_try_start > returns EINVAL. > > In fact, having two AVPackets is not needed and everything can be > handled by s->buf_pkt. > > This commit removes the local avpkt from v4l2_receive_frame(), meaning > that the ownership transfer doesn't need to be handled and the double > free is fixed. > > Signed-off-by: Andriy Gelman <andriy.gel...@gmail.com> > --- > > Sorry, forgot to squash the commit from v1 so v2 didn't apply. This is > correct version. > > Supersedes: > https://patchwork.ffmpeg.org/project/ffmpeg/patch/20200505055454.28683-1-andriy.gel...@gmail.com/ > > > libavcodec/v4l2_m2m_dec.c | 37 +++++++++++++++---------------------- > 1 file changed, 15 insertions(+), 22 deletions(-) > > diff --git a/libavcodec/v4l2_m2m_dec.c b/libavcodec/v4l2_m2m_dec.c > index 3e17e0fcac..b038efed9c 100644 > --- a/libavcodec/v4l2_m2m_dec.c > +++ b/libavcodec/v4l2_m2m_dec.c > @@ -138,14 +138,10 @@ static int v4l2_receive_frame(AVCodecContext *avctx, > AVFrame *frame) > V4L2m2mContext *s = ((V4L2m2mPriv*)avctx->priv_data)->context; > V4L2Context *const capture = &s->capture; > V4L2Context *const output = &s->output; > - AVPacket avpkt = {0}; > int ret; > > - if (s->buf_pkt.size) { > - avpkt = s->buf_pkt; > - memset(&s->buf_pkt, 0, sizeof(AVPacket)); > - } else { > - ret = ff_decode_get_packet(avctx, &avpkt); > + if (!s->buf_pkt.size) { > + ret = ff_decode_get_packet(avctx, &s->buf_pkt); > if (ret < 0 && ret != AVERROR_EOF) > return ret; > } > @@ -153,32 +149,29 @@ static int v4l2_receive_frame(AVCodecContext *avctx, > AVFrame *frame) > if (s->draining) > goto dequeue; > > - ret = ff_v4l2_context_enqueue_packet(output, &avpkt); > - if (ret < 0) { > - if (ret != AVERROR(EAGAIN)) > - return ret; > + ret = ff_v4l2_context_enqueue_packet(output, &s->buf_pkt); > + if (ret < 0 && ret != AVERROR(EAGAIN)) > + goto fail; > > - s->buf_pkt = avpkt; > - /* no input buffers available, continue dequeing */ > - } > + /* if EAGAIN don't unref packet and try to enqueue in the next iteration > */ > + if (ret != AVERROR(EAGAIN)) > + av_packet_unref(&s->buf_pkt); > > - if (avpkt.size) { > + if (!s->draining) { > ret = v4l2_try_start(avctx); > if (ret) { > - av_packet_unref(&avpkt); > - > /* cant recover */ > - if (ret == AVERROR(ENOMEM)) > - return ret; > - > - return 0; > + if (ret != AVERROR(ENOMEM)) > + ret = 0; > + goto fail; > } > } > > dequeue: > - if (!s->buf_pkt.size) > - av_packet_unref(&avpkt); > return ff_v4l2_context_dequeue_frame(capture, frame, -1); > +fail: > + av_packet_unref(&s->buf_pkt); > + return ret; > } > > static av_cold int v4l2_decode_init(AVCodecContext *avctx) > -- > 2.25.1 >
ping -- Andriy _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".
