From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.ffmpeg.org (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTPS id 9107A4F8B5 for ; Mon, 23 Jun 2025 14:24:14 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTP id A0DEC68DC3B; Mon, 23 Jun 2025 17:24:09 +0300 (EEST) Received: from relay1-d.mail.gandi.net (relay1-d.mail.gandi.net [217.70.183.193]) by ffbox0-bg.ffmpeg.org (Postfix) with ESMTPS id 2364D68DBF5 for ; Mon, 23 Jun 2025 17:24:03 +0300 (EEST) Received: by mail.gandi.net (Postfix) with ESMTPSA id 7E7E742E80 for ; Mon, 23 Jun 2025 14:24:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=niedermayer.cc; s=gm1; t=1750688642; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=G6DSuKF4qWlQv9iNGvSQ0OILnU3uUii9VafmNgQi/ko=; b=StT5/USQCtYr99nxjRiD0L38bETdHSRvFDZ6xhxTprCv5vr/jBGcVdJqOCO2uqNEI1rBSa Wnl4m4IYSpGc5uSRB0nhJv3EEcq5Dtogo2ElylWmZMbNTI9xMO5Hywa9JR3Ct5/Y4/GYpF CqBB5DSehP217LCDBs+lPB6Us3yk0S9Eo8txRdWuZGXZWi0uGXOLIXpetrDkwsFYWRRJ+a uP3PCwPEQDKutxTTpmZ22UwxvYPxLabcLhTBqsqBD4Dn8W5QIbf58+PAVsU3egcxItEr2E xecI16Oarn+g+NUmmiU5H9jgJ/4jk3mX4f5+6kCbLxTWZNbFaXNHLxawVEZQWA== Date: Mon, 23 Jun 2025 16:24:01 +0200 From: Michael Niedermayer To: FFmpeg development discussions and patches Message-ID: <20250623142401.GM29660@pb2> References: <20250619030432.2977718-1-michael@niedermayer.cc> <20250623124404.GI29660@pb2> <8c820149-1664-424a-8a6d-bf4573bab04f@gmail.com> <20250623141952.GL29660@pb2> MIME-Version: 1.0 In-Reply-To: <20250623141952.GL29660@pb2> X-GND-State: clean X-GND-Score: -85 X-GND-Cause: gggruggvucftvghtrhhoucdtuddrgeeffedrtddvgddujedvhecutefuodetggdotefrodftvfcurfhrohhfihhlvgemucfitefpfffkpdcuggftfghnshhusghstghrihgsvgenuceurghilhhouhhtmecufedtudenucesvcftvggtihhpihgvnhhtshculddquddttddmnegfrhhlucfvnfffucdludehmdenucfjughrpeffhffvuffkfhggtggujgesghdtreertddtvdenucfhrhhomhepofhitghhrggvlhcupfhivgguvghrmhgrhigvrhcuoehmihgthhgrvghlsehnihgvuggvrhhmrgihvghrrdgttgeqnecuggftrfgrthhtvghrnheptefggedvffeiueffvefhiedtgfefjedukeefgeetgeevgeejgeekvdevjeelveeknecuffhomhgrihhnpehgihhthhhusgdrtghomhenucfkphepgedurdeiiedrieejrdduudefnecuvehluhhsthgvrhfuihiivgeptdenucfrrghrrghmpehinhgvthepgedurdeiiedrieejrdduudefpdhhvghloheplhhotggrlhhhohhsthdpmhgrihhlfhhrohhmpehmihgthhgrvghlsehnihgvuggvrhhmrgihvghrrdgttgdpnhgspghrtghpthhtohepuddprhgtphhtthhopehffhhmphgvghdquggvvhgvlhesfhhfmhhpvghgrdhorhhg X-GND-Sasl: michael@niedermayer.cc Subject: Re: [FFmpeg-devel] [PATCH 1/4] avformat/iamf_parse: Check extradata size 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="===============2605764192146681583==" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: --===============2605764192146681583== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="ChGgVEaj47PkCkNc" Content-Disposition: inline --ChGgVEaj47PkCkNc Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Jun 23, 2025 at 04:19:52PM +0200, Michael Niedermayer wrote: > On Mon, Jun 23, 2025 at 09:47:55AM -0300, James Almer wrote: > > On 6/23/2025 9:44 AM, Michael Niedermayer wrote: > > > On Fri, Jun 20, 2025 at 12:28:13AM +0200, Andreas Rheinhardt wrote: > > > > Michael Niedermayer: > > > > > Fixes: Assertion n>=3D0 && n<=3D32 failed at ./libavcodec/get_bit= s.h:406 > > > > > Fixes: 398527871/clusterfuzz-testcase-minimized-ffmpeg_dem_IAMF_f= uzzer-6602025714647040 > > > > >=20 > > > > > Found-by: continuous fuzzing process https://github.com/google/os= s-fuzz/tree/master/projects/ffmpeg > > > > > Signed-off-by: Michael Niedermayer > > > > > --- > > > > > libavformat/iamf_parse.c | 2 ++ > > > > > 1 file changed, 2 insertions(+) > > > > >=20 > > > > > diff --git a/libavformat/iamf_parse.c b/libavformat/iamf_parse.c > > > > > index 71497876ac3..330e01733dd 100644 > > > > > --- a/libavformat/iamf_parse.c > > > > > +++ b/libavformat/iamf_parse.c > > > > > @@ -305,6 +305,8 @@ static int update_extradata(AVCodecParameters= *codecpar) > > > > > skip_bits(&gb, 4); > > > > > put_bits(&pb, 4, codecpar->ch_layout.nb_channels); // s= et channel config > > > > > ret =3D put_bits_left(&pb); > > > > > + if (ret < 0) > > > > > + return AVERROR_INVALIDDATA; > > > > > while (ret >=3D 32) { > > > > > put_bits32(&pb, get_bits_long(&gb, 32)); > > > > > ret -=3D 32; > > > >=20 > > > > There is only one way for put_bits_left() to return a negative valu= e: If > > > > there is more data in the internal buffer than can be written out. = And > > > > this scenario is already a violation of the PutBit API. Given that = the > > > > size of the internal buffer depends upon the arch, it could be that= one > > > > would have already hit an assert in case one is not using x64. In o= ther > > > > words, your check is too late. > > >=20 > > > the patches puprose was mainly to show that > > > 3f9420132441345b7ccd57001f230bb98f655696 > > > was insufficient to fix 398527871 > > >=20 > > > I do not expect my patch would be the correct solution even if the > > > check is done earlier. IAMF is cursed > >=20 > > Does increasing buf from 6 bytes to 8 or more fix it? I see putbits may= do > > an AV_W*64(), so six bytes sounds like it was never safe. >=20 > i set buffer to 1000 and it still fails with put_bits_left() > returning -19 >=20 > what will fix this specific case is: > - if (ret =3D=3D 0x0f) > - put_bits(&pb, 24, get_bits(&gb, 24)); > + if (ret =3D=3D 0x0f) { > + if (get_bits_left(&gb) >=3D 24+4+4) this should be only one +4 thx [...] --=20 Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety -- Benjamin Franklin --ChGgVEaj47PkCkNc Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABEKAB0WIQSf8hKLFH72cwut8TNhHseHBAsPqwUCaFljgQAKCRBhHseHBAsP qzxVAJ9I25DH9CSGNcngsSJ1n7WR1lVWKACeJaw7O6uudAR3U7J/bHHc3WWwOys= =lPG/ -----END PGP SIGNATURE----- --ChGgVEaj47PkCkNc-- --===============2605764192146681583== 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". --===============2605764192146681583==--