From patchwork Wed Oct 2 21:37:38 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michael Niedermayer X-Patchwork-Id: 15469 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 C89C7447F21 for ; Thu, 3 Oct 2019 00:45:29 +0300 (EEST) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id B1A4E6880EC; Thu, 3 Oct 2019 00:45:29 +0300 (EEST) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from vie01a-dmta-pe06-3.mx.upcmail.net (vie01a-dmta-pe06-3.mx.upcmail.net [84.116.36.16]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 2499E687FD1 for ; Thu, 3 Oct 2019 00:45:23 +0300 (EEST) Received: from [172.31.216.235] (helo=vie01a-pemc-psmtp-pe12.mail.upcmail.net) by vie01a-dmta-pe06.mx.upcmail.net with esmtp (Exim 4.92) (envelope-from ) id 1iFmL8-0002aa-1Z for ffmpeg-devel@ffmpeg.org; Wed, 02 Oct 2019 23:39:18 +0200 Received: from localhost ([213.47.68.29]) by vie01a-pemc-psmtp-pe12.mail.upcmail.net with ESMTP id FmKAiR0TvwlysFmKAiKYx4; Wed, 02 Oct 2019 23:38:18 +0200 X-Env-Mailfrom: michael@niedermayer.cc X-Env-Rcptto: ffmpeg-devel@ffmpeg.org X-SourceIP: 213.47.68.29 X-CNFS-Analysis: v=2.3 cv=E5OzWpVl c=1 sm=1 tr=0 a=2hcxjKEKjp0CzLx6oWAm4g==:117 a=2hcxjKEKjp0CzLx6oWAm4g==:17 a=jpOVt7BSZ2e4Z31A5e1TngXxSK0=:19 a=MKtGQD3n3ToA:10 a=1oJP67jkp3AA:10 a=GEAsPZ9sns4A:10 a=ZZnuYtJkoWoA:10 a=nZOtpAppAAAA:20 a=dn0XP3Nya0-0vA9gSe8A:9 a=1fhp2MxaeJtTNGEnv6mo:22 a=Z5ABNNGmrOfJ6cZ5bIyy:22 a=UDnyf2zBuKT2w-IlGP_r:22 From: Michael Niedermayer To: FFmpeg development discussions and patches Date: Wed, 2 Oct 2019 23:37:38 +0200 Message-Id: <20191002213740.17936-3-michael@niedermayer.cc> X-Mailer: git-send-email 2.23.0 In-Reply-To: <20191002213740.17936-1-michael@niedermayer.cc> References: <20191002213740.17936-1-michael@niedermayer.cc> MIME-Version: 1.0 X-CMAE-Envelope: MS4wfBmjihGFfEt40+BWni1xco13k6D66FZv72rh6oT/jX0PtekX43mzxDqmpyrSwrj18AFEOvoSWlF4qgEgQkHFPaaOey2FwVGNoCvLIZ9pfbecIQE9ddpO 6MJbyCRzdRM2BM6J24xUo6U0AS4H7ULVHit9BkBy7YDLVNK1ow68Pr83 Subject: [FFmpeg-devel] [PATCH 3/5] avcodec/dstdec: Check for input exhaustion 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" Fixes: Timeout (239sec -> 16sec) Fixes: 17811/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_DST_fuzzer-5715508149616640 Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg Signed-off-by: Michael Niedermayer --- libavcodec/dstdec.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/libavcodec/dstdec.c b/libavcodec/dstdec.c index 8a1bc6a738..48271b10f7 100644 --- a/libavcodec/dstdec.c +++ b/libavcodec/dstdec.c @@ -56,6 +56,7 @@ static const int8_t probs_code_pred_coeff[3][3] = { typedef struct ArithCoder { unsigned int a; unsigned int c; + int overread; } ArithCoder; typedef struct Table { @@ -172,6 +173,7 @@ static void ac_init(ArithCoder *ac, GetBitContext *gb) { ac->a = 4095; ac->c = get_bits(gb, 12); + ac->overread = 0; } static av_always_inline void ac_get(ArithCoder *ac, GetBitContext *gb, int p, int *e) @@ -191,6 +193,8 @@ static av_always_inline void ac_get(ArithCoder *ac, GetBitContext *gb, int p, in if (ac->a < 2048) { int n = 11 - av_log2(ac->a); ac->a <<= n; + if (get_bits_left(gb) < n) + ac->overread ++; ac->c = (ac->c << n) | get_bits(gb, n); } } @@ -339,6 +343,9 @@ static int decode_frame(AVCodecContext *avctx, void *data, prob = 128; } + if (ac->overread > 16) + return AVERROR_INVALIDDATA; + ac_get(ac, gb, prob, &residual); v = ((predict >> 15) ^ residual) & 1; dsd[((i >> 3) * channels + ch) << 2] |= v << (7 - (i & 0x7 ));