From patchwork Thu May 16 22:29:55 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andreas Rheinhardt X-Patchwork-Id: 13176 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 D53F0449B3C for ; Fri, 17 May 2019 01:51:19 +0300 (EEST) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id BF06768A607; Fri, 17 May 2019 01:51:19 +0300 (EEST) X-Original-To: ffmpeg-devel@ffmpeg.org Delivered-To: ffmpeg-devel@ffmpeg.org Received: from mail-wm1-f65.google.com (mail-wm1-f65.google.com [209.85.128.65]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 81C1F68A70E for ; Fri, 17 May 2019 01:51:18 +0300 (EEST) Received: by mail-wm1-f65.google.com with SMTP id x64so5116064wmb.5 for ; Thu, 16 May 2019 15:51:18 -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=sqLNM64GgkogAaHeMB33XHRi3Ne2wg3sRbMVoXf9YAg=; b=pDcmsJT8goNyb5yCLnJQMV42vylgoZokoRCjw1OEMJhitYgI+VnXAkSezBGEVbXc5g 4YjqSIrSKiliBh3Dwepo94/Oj8q6Tdi6ozElVfVp0UCoxEFZY0HAon2PC3gjrMbBQK0u tU4zPBwj2qeZx8FB7Zxwzu/UKgWnxD9AD2dhrh+2T9tfpWFao0g6XhX0z++3B9UCYL/F XY3fT5SLVy9fEuDI2bKTfaUoy6wyBqTy+SHVnk+BAc5Am4VzFX/DvLfg5MexFnO77EzM sVMoBs+YnnfCOgWisj38SViXoy1q/OoGZrg0gALpGkGeZ3lmnuRwIt8du1IWny4p2yq9 pLqw== 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=sqLNM64GgkogAaHeMB33XHRi3Ne2wg3sRbMVoXf9YAg=; b=aueoeKfP6pKaa/qu5kv9Rv8zz7N/JE6FFVwf5p82zjg3fquvo7F8Ms+PhMnGmZb1ih wZMLFVM22ZQDG8sUJzrmlFCOgJgSf7Nt7S4eAqMof8mSGno6sYZc6bRIBCIcaZ3gBhh6 oHPgjU7qB8xWtSrvzXkoSg+N2eoqWYMXI8RCLv0cwtPgDI9MYp9u8nXmndGN56bFrloD NmL7NsMpl9KPDM+LuSyUHm6Mf1l2qITb/y+0Gc41ukiId7P7MRe47q3NB4TxQvPklU07 uMl/U0HBX59BObnyLNreTvaTXNKhbxfiRDTESZh8uR4cSYdBShgE8ozd4MbwFmhFJlnF M9GA== X-Gm-Message-State: APjAAAU2GU1ajDw6QnqYwlaF8vkYYGi5lWXF89OfnuRv3QoPI1njP8ww ez9SVpbSbuwhfJagat04s7sZulhw X-Google-Smtp-Source: APXvYqzCeWVEoaJsLPH87DTxUuLN29JxwvuAbvbkXwSzmvPJqU+g4LT/gxgcyhJlj6WzT38qkw2i1g== X-Received: by 2002:a1c:2d45:: with SMTP id t66mr90764wmt.106.1558046591010; Thu, 16 May 2019 15:43:11 -0700 (PDT) Received: from localhost.localdomain (ipbcc18715.dynamic.kabel-deutschland.de. [188.193.135.21]) by smtp.gmail.com with ESMTPSA id i185sm11168725wmg.32.2019.05.16.15.43.10 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Thu, 16 May 2019 15:43:10 -0700 (PDT) From: Andreas Rheinhardt To: ffmpeg-devel@ffmpeg.org Date: Fri, 17 May 2019 00:29:55 +0200 Message-Id: <20190516223018.30827-12-andreas.rheinhardt@gmail.com> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190516223018.30827-1-andreas.rheinhardt@gmail.com> References: <20190516223018.30827-1-andreas.rheinhardt@gmail.com> MIME-Version: 1.0 Subject: [FFmpeg-devel] [PATCH 11/37] 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 | 76 +++++++++++++++++++++++---------------- 1 file changed, 45 insertions(+), 31 deletions(-) diff --git a/libavformat/matroskadec.c b/libavformat/matroskadec.c index 0f7decb212..431e742a2d 100644 --- a/libavformat/matroskadec.c +++ b/libavformat/matroskadec.c @@ -820,33 +820,30 @@ 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; } @@ -855,9 +852,27 @@ 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_EOF; } /** @@ -868,7 +883,7 @@ 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; @@ -1010,7 +1025,7 @@ 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); } /* @@ -1057,7 +1072,7 @@ 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 && @@ -3353,10 +3368,9 @@ 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; @@ -3717,7 +3731,7 @@ 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); @@ -3935,7 +3949,7 @@ 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);