From patchwork Thu Nov 29 01:32:10 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Niedermayer X-Patchwork-Id: 11214 Return-Path: X-Original-To: patchwork@ffaux-bg.ffmpeg.org Delivered-To: patchwork@ffaux-bg.ffmpeg.org Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by ffaux.localdomain (Postfix) with ESMTP id B4A2644DA30 for ; Thu, 29 Nov 2018 03:34:02 +0200 (EET) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 43A7068A56A; Thu, 29 Nov 2018 03:34:03 +0200 (EET) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from vie01a-dmta-pe08-1.mx.upcmail.net (vie01a-dmta-pe08-1.mx.upcmail.net [84.116.36.20]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id AAB2D688354 for ; Thu, 29 Nov 2018 03:33:56 +0200 (EET) Received: from [172.31.216.235] (helo=vie01a-pemc-psmtp-pe12.mail.upcmail.net) by vie01a-dmta-pe08.mx.upcmail.net with esmtp (Exim 4.88) (envelope-from ) id 1gSBDO-0001Xa-0N for ffmpeg-devel@ffmpeg.org; Thu, 29 Nov 2018 02:34:02 +0100 Received: from localhost ([213.47.41.20]) by vie01a-pemc-psmtp-pe12.mail.upcmail.net with ESMTP id SBCQgDEhlkosQSBCQgICx7; Thu, 29 Nov 2018 02:33:02 +0100 X-Env-Mailfrom: michael@niedermayer.cc X-Env-Rcptto: ffmpeg-devel@ffmpeg.org X-SourceIP: 213.47.41.20 X-CNFS-Analysis: v=2.3 cv=NNQEBHyg c=1 sm=1 tr=0 a=I1eytVlZLDX1BM2VTtTtSw==:117 a=I1eytVlZLDX1BM2VTtTtSw==:17 a=MKtGQD3n3ToA:10 a=1oJP67jkp3AA:10 a=GEAsPZ9sns4A:10 a=ZZnuYtJkoWoA:10 a=nZOtpAppAAAA:20 a=gFy7AMl7KoJRQFxIJeIA:9 a=pHzHmUro8NiASowvMSCR:22 a=nt3jZW36AmriUCFCBwmW:22 From: Michael Niedermayer To: FFmpeg development discussions and patches Date: Thu, 29 Nov 2018 02:32:10 +0100 Message-Id: <20181129013210.15887-1-michael@niedermayer.cc> X-Mailer: git-send-email 2.19.2 MIME-Version: 1.0 X-CMAE-Envelope: MS4wfPxr2PBiXa4NzpJB/sAAQRuR+mWPjKNo5qJhlaGLtCfNgNw6qUnr62/+yRmLIJzkkFEHwhhnDWSp8fB+2z1HT8l/luJlkFuVGERA+K/gB1bo9BLKkuyI TDHA49iyOVWBeWflHAQ8FA7JDVZHdxc5wZSAhhvLXAMXV1lGEiUqkywi Subject: [FFmpeg-devel] [PATCH] avcodec/msmpeg4dec: Skip frame if its smaller than 1/8 of the minimal size X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Frames that small are not valid and of limited use for error concealment, while being very computationally intensive to process. Fixes: Timeout Fixes: 11318/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MSMPEG4V1_fuzzer-5710884555456512 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- libavcodec/msmpeg4dec.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/libavcodec/msmpeg4dec.c b/libavcodec/msmpeg4dec.c index 457a37e745..16b67192b5 100644 --- a/libavcodec/msmpeg4dec.c +++ b/libavcodec/msmpeg4dec.c @@ -412,6 +412,14 @@ int ff_msmpeg4_decode_picture_header(MpegEncContext * s) { int code; + // at minimum one bit per macroblock is required at least in a valid frame, + // we discard frames much smaller than this. Frames smaller than 1/8 of the + // smallest "black/skip" frame generally contain not much recoverable content + // while at the same time they have the highest computational requirements + // per byte + if (get_bits_left(&s->gb) * 8LL < (s->width+15)/16 * ((s->height+15)/16)) + return AVERROR_INVALIDDATA; + if(s->msmpeg4_version==1){ int start_code = get_bits_long(&s->gb, 32); if(start_code!=0x00000100){