From patchwork Sun Jun 23 23:42:29 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Rheinhardt X-Patchwork-Id: 13684 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 7753B448B31 for ; Mon, 24 Jun 2019 02:43:48 +0300 (EEST) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 5332968A544; Mon, 24 Jun 2019 02:43:48 +0300 (EEST) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from mail-wr1-f65.google.com (mail-wr1-f65.google.com [209.85.221.65]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 9A276689946 for ; Mon, 24 Jun 2019 02:43:41 +0300 (EEST) Received: by mail-wr1-f65.google.com with SMTP id n4so10702673wrs.3 for ; Sun, 23 Jun 2019 16:43:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=6knnvwFIZo+BFv1hEcZx/YpHI9YK1VVzdoOkE2fjU3s=; b=rG1Fxh2ld5gQgkfhxSqaTVT70R4usiaHeXhuQ2r1jfB3s6m+K6xpFFtHZG6PXN4JVN jv5HXfhf519B5EcRty4gBngozWQ5hkg5if/HmzNVwdLlDXwbHOckDwBvchUCXBB2cJVc 8OlO/aJW1q42WtG5hjjrhm+lK46+XUpIBmDTy68hqHLEUB1rhrLnIOhcAjeUQH/zO5mZ D9LrfmNG+7m4L/Ii5tj7npmjZKkjnC+sHeOsozM21iS+96ELB1iYnGxtIrwc75ZUzrdE theM4lP3hPZQLCwoDaUHX/Lm5J4a6rBQhseQGKvoaY6yrWIMk/N0F5oqHj7BWbImNtdu wMTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=6knnvwFIZo+BFv1hEcZx/YpHI9YK1VVzdoOkE2fjU3s=; b=HOOh6qGVMyoSC/epf5QAbuIU3AtAQqwX7iV6iPYFrIFyP8koI63YxmUZtHNCjDwxe/ rFMiTdfwZkTulwLLTzg7BAf6yN1KcQh+vxdZA3QgLBB9vOmcXk44MHoXJYcq04rJKRGT LZ6TsEkdKddwh3k88niIs8nN8nQsnNA5Sia3e7TKeMzI5OET1hmgtpLVPm77fHClFyBi 6FTLPgs/oaJEJRWQUBBmo9HSnt2fmu1RmhmGHcRwEyKl411EDBWmcbBoH2iqmGKuLahL UbRsT2HLGma1KNdxnnu/Go+hIRPQ+lTdjc/lxBuDiRjbAbBERvl5f5jDVbxQF0tb1tXG z7Sw== X-Gm-Message-State: APjAAAW4tw6SnzcXMfBS6OmJBNYfp2xjA0Bs1bTL7eatI0c5EliKP++R unpphOZ5utxM6WCFr83F8VMTfbd5 X-Google-Smtp-Source: APXvYqyGn/TMgfBWGJOUGH1bK2XY9PL0s18MIw5eGD2tykPsOCUWfCuFqHxGH9MeqNr4erPS0aMHyg== X-Received: by 2002:adf:e8c8:: with SMTP id k8mr78621223wrn.285.1561333420885; Sun, 23 Jun 2019 16:43:40 -0700 (PDT) Received: from localhost.localdomain (ipbcc063db.dynamic.kabel-deutschland.de. [188.192.99.219]) by smtp.gmail.com with ESMTPSA id b6sm7087102wrx.85.2019.06.23.16.43.39 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Sun, 23 Jun 2019 16:43:39 -0700 (PDT) From: Andreas Rheinhardt To: ffmpeg-devel@ffmpeg.org Date: Mon, 24 Jun 2019 01:42:29 +0200 Message-Id: <20190623234231.6348-1-andreas.rheinhardt@gmail.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <2b14f7af-4e9a-bebd-43f5-c2b5c761c915@gmail.com> References: <2b14f7af-4e9a-bebd-43f5-c2b5c761c915@gmail.com> MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH 11/13] avformat/matroskadec: Improve read error/EOF checks I 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 Cc: Andreas Rheinhardt Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" ebml_read_num had a number of flaws: 1. The check for read errors/EOF was totally wrong. E.g. an EBML number beginning with the invalid 0x00 would be considered a read error, although it is just invalid data. 2. The check for read errors/EOF was done just once, after reading the first byte of the EBML number. But errors/EOF can happen inbetween, of course, and this wasn't checked. 3. There was no way to distinguish when EOF should be an error (because the data has to be there) for which an error message should be emitted and when it is not necessarily an error (namely during parsing of EBML IDs). Such a possibility has been added and used. All this was fixed; furthermore, the error messages for invalid EBML numbers were improved and useless initializations were removed. Signed-off-by: Andreas Rheinhardt --- libavformat/matroskadec.c | 78 +++++++++++++++++++++++---------------- 1 file changed, 47 insertions(+), 31 deletions(-) diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c index f0906675e6..b923a9edff 100644 --- a/libavformat/matroskadec.c +++ b/libavformat/matroskadec.c @@ -796,33 +796,30 @@ static int ebml_level_end(MatroskaDemuxContext *matroska) * Returns: number of bytes read, < 0 on error */ static int ebml_read_num(MatroskaDemuxContext *matroska, AVIOContext *pb, - int max_size, uint64_t *number) + int max_size, uint64_t *number, int eof_forbidden) { - int read = 1, n = 1; - uint64_t total = 0; + int read, n = 1; + uint64_t total; + int64_t pos; - /* The first byte tells us the length in bytes - avio_r8() can normally - * return 0, but since that's not a valid first ebmlID byte, we can - * use it safely here to catch EOS. */ - if (!(total = avio_r8(pb))) { - /* we might encounter EOS here */ - if (!avio_feof(pb)) { - int64_t pos = avio_tell(pb); - av_log(matroska->ctx, AV_LOG_ERROR, - "Read error at pos. %"PRIu64" (0x%"PRIx64")\n", - pos, pos); - return pb->error ? pb->error : AVERROR(EIO); - } - return AVERROR_EOF; - } + /* The first byte tells us the length in bytes - except when it is zero. */ + total = avio_r8(pb); + if (pb->eof_reached) + goto err; /* get the length of the EBML number */ - read = 8 - ff_log2_tab[total]; - if (read > max_size) { - int64_t pos = avio_tell(pb) - 1; - av_log(matroska->ctx, AV_LOG_ERROR, - "Invalid EBML number size tag 0x%02x at pos %"PRIu64" (0x%"PRIx64")\n", - (uint8_t) total, pos, pos); + if (!total || (read = 8 - ff_log2_tab[total]) > max_size) { + pos = avio_tell(pb) - 1; + if (!total) { + av_log(matroska->ctx, AV_LOG_ERROR, + "0x00 at pos %"PRId64" (0x%"PRIx64") invalid as first byte " + "of an EBML number\n", pos, pos); + } else { + av_log(matroska->ctx, AV_LOG_ERROR, + "Length %d indicated by an EBML number's first byte 0x%02x " + "at pos %"PRId64" (0x%"PRIx64") exceeds max length %d.\n", + read, (uint8_t) total, pos, pos, max_size); + } return AVERROR_INVALIDDATA; } @@ -831,9 +828,29 @@ static int ebml_read_num(MatroskaDemuxContext *matroska, AVIOContext *pb, while (n++ < read) total = (total << 8) | avio_r8(pb); + if (pb->eof_reached) { + eof_forbidden = 1; + goto err; + } + *number = total; return read; + +err: + pos = avio_tell(pb); + if (pb->error) { + av_log(matroska->ctx, AV_LOG_ERROR, + "Read error at pos. %"PRIu64" (0x%"PRIx64")\n", + pos, pos); + return pb->error; + } + if (eof_forbidden) { + av_log(matroska->ctx, AV_LOG_ERROR, "File ended prematurely " + "at pos. %"PRIu64" (0x%"PRIx64")\n", pos, pos); + return AVERROR(EIO); + } + return AVERROR_EOF; } /** @@ -844,7 +861,7 @@ static int ebml_read_num(MatroskaDemuxContext *matroska, AVIOContext *pb, static int ebml_read_length(MatroskaDemuxContext *matroska, AVIOContext *pb, uint64_t *number) { - int res = ebml_read_num(matroska, pb, 8, number); + int res = ebml_read_num(matroska, pb, 8, number, 1); if (res > 0 && *number + 1 == 1ULL << (7 * res)) *number = EBML_UNKNOWN_LENGTH; return res; @@ -986,7 +1003,7 @@ static int matroska_ebmlnum_uint(MatroskaDemuxContext *matroska, { AVIOContext pb; ffio_init_context(&pb, data, size, 0, NULL, NULL, NULL, NULL); - return ebml_read_num(matroska, &pb, FFMIN(size, 8), num); + return ebml_read_num(matroska, &pb, FFMIN(size, 8), num, 1); } /* @@ -1033,7 +1050,7 @@ static int ebml_parse(MatroskaDemuxContext *matroska, EbmlSyntax *syntax, { if (!matroska->current_id) { uint64_t id; - int res = ebml_read_num(matroska, matroska->ctx->pb, 4, &id); + int res = ebml_read_num(matroska, matroska->ctx->pb, 4, &id, 0); if (res < 0) { // in live mode, finish parsing if EOF is reached. return (matroska->is_live && matroska->ctx->pb->eof_reached && @@ -3325,10 +3342,9 @@ static int matroska_parse_block(MatroskaDemuxContext *matroska, AVBufferRef *buf uint64_t num; int trust_default_duration = 1; - if ((n = matroska_ebmlnum_uint(matroska, data, size, &num)) < 0) { - av_log(matroska->ctx, AV_LOG_ERROR, "EBML block data error\n"); + if ((n = matroska_ebmlnum_uint(matroska, data, size, &num)) < 0) return n; - } + data += n; size -= n; @@ -3650,7 +3666,7 @@ static int webm_clusters_start_with_keyframe(AVFormatContext *s) AVPacket *pkt; avio_seek(s->pb, cluster_pos, SEEK_SET); // read cluster id and length - read = ebml_read_num(matroska, matroska->ctx->pb, 4, &cluster_id); + read = ebml_read_num(matroska, matroska->ctx->pb, 4, &cluster_id, 1); if (read < 0 || cluster_id != 0xF43B675) // done with all clusters break; read = ebml_read_length(matroska, matroska->ctx->pb, &cluster_length); @@ -3868,7 +3884,7 @@ static int webm_dash_manifest_cues(AVFormatContext *s, int64_t init_range) // cues_end is inclusive and the above sum is reduced by 1. uint64_t cues_length, cues_id; int bytes_read; - bytes_read = ebml_read_num (matroska, matroska->ctx->pb, 4, &cues_id); + bytes_read = ebml_read_num (matroska, matroska->ctx->pb, 4, &cues_id, 1); if (bytes_read < 0 || cues_id != (MATROSKA_ID_CUES & 0xfffffff)) return bytes_read < 0 ? bytes_read : AVERROR_INVALIDDATA; bytes_read = ebml_read_length(matroska, matroska->ctx->pb, &cues_length);