From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id E731F47208 for ; Sat, 30 Sep 2023 22:29:08 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 66E2D68CD11; Sun, 1 Oct 2023 01:29:05 +0300 (EEST) Received: from relay7-d.mail.gandi.net (relay7-d.mail.gandi.net [217.70.183.200]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 8084368CCA9 for ; Sun, 1 Oct 2023 01:28:58 +0300 (EEST) Received: by mail.gandi.net (Postfix) with ESMTPSA id 8FD7720004 for ; Sat, 30 Sep 2023 22:28:57 +0000 (UTC) Date: Sun, 1 Oct 2023 00:28:56 +0200 From: Michael Niedermayer To: FFmpeg development discussions and patches Message-ID: <20230930222856.GN3543730@pb2> References: <20230929232001.23197-1-michael@niedermayer.cc> <47b96a8-db6b-aa20-d48-a6d60f0e84e@passwd.hu> <20230930140403.GK3543730@pb2> <20230930143143.GL3543730@pb2> <169610511838.6638.13529422310033823704@lain.khirnov.net> MIME-Version: 1.0 In-Reply-To: <169610511838.6638.13529422310033823704@lain.khirnov.net> X-GND-Sasl: michael@niedermayer.cc Subject: Re: [FFmpeg-devel] [PATCH 1/6] avformat/avidec: support huge durations X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 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 Content-Type: multipart/mixed; boundary="===============5299097392666309060==" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: --===============5299097392666309060== Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="OE5XN2KVoD5QaTkR" Content-Disposition: inline --OE5XN2KVoD5QaTkR Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Sat, Sep 30, 2023 at 10:18:38PM +0200, Anton Khirnov wrote: > Quoting Michael Niedermayer (2023-09-30 16:31:43) > > On Sat, Sep 30, 2023 at 04:04:03PM +0200, Michael Niedermayer wrote: > > > On Sat, Sep 30, 2023 at 11:35:19AM +0200, Marton Balint wrote: > > > >=20 > > > >=20 > > > > On Sat, 30 Sep 2023, Michael Niedermayer wrote: > > > >=20 > > > > > Fixes: signed integer overflow: 109817402400 * 301990077 cannot b= e represented in type 'long long' > > > > > Fixes: 51896/clusterfuzz-testcase-minimized-ffmpeg_dem_AVI_fuzzer= -6706191715139584 > > > > >=20 > > > > > Found-by: continuous fuzzing process https://github.com/google/os= s-fuzz/tree/master/projects/ffmpeg > > > > > Signed-off-by: Michael Niedermayer > > > > > --- > > > > > libavformat/avidec.c | 12 ++++++++++-- > > > > > 1 file changed, 10 insertions(+), 2 deletions(-) > > > > >=20 > > > > > diff --git a/libavformat/avidec.c b/libavformat/avidec.c > > > > > index 00bd7a98a9d..cfc693842b7 100644 > > > > > --- a/libavformat/avidec.c > > > > > +++ b/libavformat/avidec.c > > > > > @@ -27,6 +27,7 @@ > > > > > #include "libavutil/avstring.h" > > > > > #include "libavutil/opt.h" > > > > > #include "libavutil/dict.h" > > > > > +#include "libavutil/integer.h" > > > > > #include "libavutil/internal.h" > > > > > #include "libavutil/intreadwrite.h" > > > > > #include "libavutil/mathematics.h" > > > > > @@ -476,7 +477,7 @@ static int calculate_bitrate(AVFormatContext = *s) > > > > > AVStream *st =3D s->streams[i]; > > > > > FFStream *const sti =3D ffstream(st); > > > > > int64_t duration; > > > > > - int64_t bitrate; > > > > > + int64_t bitrate =3D 0; > > > > >=20 > > > > > for (j =3D 0; j < sti->nb_index_entries; j++) > > > > > len +=3D sti->index_entries[j].size; > > > > > @@ -484,7 +485,14 @@ static int calculate_bitrate(AVFormatContext= *s) > > > > > if (sti->nb_index_entries < 2 || st->codecpar->bit_rate >= 0) > > > > > continue; > > > > > duration =3D sti->index_entries[j-1].timestamp - sti->ind= ex_entries[0].timestamp; > > > > > - bitrate =3D av_rescale(8*len, st->time_base.den, duratio= n * st->time_base.num); > > > > > + if (INT64_MAX / duration >=3D st->time_base.num) { > > > > > + bitrate =3D av_rescale(8*len, st->time_base.den, dur= ation * st->time_base.num); > > > >=20 > > > > Why not always use the AVInteger version? This is not performance s= ensitive > > > > as far as I see. > > >=20 > > > We can, i will have to fix the rounding though so it matches av_resca= le() > >=20 > > will apply this with just AVInteger and fixed rounding with my next pus= h probably >=20 > This seems MUCH less readable to me. we can add a av_rescale_2den() >=20 > Do we expect such huge durations in actual files rather than fuzzed > ones? no, i dont expect that. > Would it not be better to just not export the duration at all when > the computation would overflow? Better ? i dont know if i scale that idea up and replace EVERY computation with a subset that seems enough and prettier. I think that would not result in overall very robust or clean code. If its better to do it just here i dont know but ill do whatever people prefer thx [...] --=20 Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB I know you won't believe me, but the highest form of Human Excellence is to question oneself and others. -- Socrates --OE5XN2KVoD5QaTkR Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABEIAB0WIQSf8hKLFH72cwut8TNhHseHBAsPqwUCZRihJAAKCRBhHseHBAsP qyn0AKCAkWJvERAOCJpbm2NbdwlELsxibACeIMwaEKybZ/Rr2kbPu+WbcieSErU= =qyJs -----END PGP SIGNATURE----- --OE5XN2KVoD5QaTkR-- --===============5299097392666309060== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe". --===============5299097392666309060==--