From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id E3BB9C41535 for ; Tue, 20 Dec 2022 20:30:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233685AbiLTUaX (ORCPT ); Tue, 20 Dec 2022 15:30:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:59646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229543AbiLTUaW (ORCPT ); Tue, 20 Dec 2022 15:30:22 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 08506BCBB; Tue, 20 Dec 2022 12:30:21 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id B6FCCB8197A; Tue, 20 Dec 2022 20:30:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3B110C433D2; Tue, 20 Dec 2022 20:30:18 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1671568218; bh=sru7LQzWJgHhTjq6GGgq1igtkj+AD/SkpfcWXzTJ0tE=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=dc346weOE7CjZdtk6aJU8cIiWUvyMmIAz1qs8SsVmoOGwSibZi2W8kzYotUXZdMet r4DxSdAYwFEQRnWz9P5axU3/iN/AZB+/OwfNtBVn5k/6UhkgkOLGX9r3foFlUl3Pv1 qvIyr8zoJgnWyVNmKCokwOqjkW4qIbnEtfFEvYKquv6wIbX5qzL9IKdzQPwdahl4Nk 9p+46oNa5XnMqkbit+txcwdAe0Hwaxoc6fJJn0RxJvXsp0m9Vw8P9b3w+BC0QeajCT AEvkM4BPuj6dh/LyhDxyrXJABgJV9XMwzNdOgZ4RMkSYMdHQqFLcu+QFce0fhm3+v6 N3Xqgep6f2rCg== Date: Tue, 20 Dec 2022 20:30:16 +0000 From: Eric Biggers To: Roberto Sassu Cc: Herbert Xu , dhowells@redhat.com, davem@davemloft.net, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, paul@paul-moore.com, jmorris@namei.org, serge@hallyn.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, keyrings@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, Roberto Sassu , Tadeusz Struk Subject: Re: [PATCH] lib/mpi: Fix buffer overrun when SG is too long Message-ID: References: <20221209150633.1033556-1-roberto.sassu@huaweicloud.com> <0f80852578436dbba7a0fce03d86c3fa2d38c571.camel@huaweicloud.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Precedence: bulk List-ID: On Tue, Dec 20, 2022 at 11:36:50AM +0100, Roberto Sassu wrote: > On 12/20/2022 8:24 AM, Herbert Xu wrote: > > On Mon, Dec 19, 2022 at 09:49:29AM +0100, Roberto Sassu wrote: > > > > > > do you have any news on this bug? > > > > Thanks for the reminder. Could you please try this patch? > > Tried, could not boot the UML kernel. > > After looking, it seems we have to call sg_miter_stop(). Or alternatively, > we could let sg_miter_next() be called but not writing anything inside the > loop. > > With either of those fixes, the tests pass (using one scatterlist). > > Roberto > > > ---8<--- > > The helper mpi_read_raw_from_sgl ignores the second parameter > > nbytes when reading the SG list and may overrun its own buffer > > because it only allocates enough memory according to nbytes. > > > > Fixes: 2d4d1eea540b ("lib/mpi: Add mpi sgl helpers") > > Reported-by: Roberto Sassu > > Signed-off-by: Herbert Xu > > > > diff --git a/lib/mpi/mpicoder.c b/lib/mpi/mpicoder.c > > index 39c4c6731094..6bffc68c1a5a 100644 > > --- a/lib/mpi/mpicoder.c > > +++ b/lib/mpi/mpicoder.c > > @@ -494,17 +494,15 @@ MPI mpi_read_raw_from_sgl(struct scatterlist *sgl, unsigned int nbytes) > > val->sign = 0; > > val->nlimbs = nlimbs; > > - if (nbytes == 0) > > - return val; > > - > > j = nlimbs - 1; > > a = 0; > > z = BYTES_PER_MPI_LIMB - nbytes % BYTES_PER_MPI_LIMB; > > z %= BYTES_PER_MPI_LIMB; > > - while (sg_miter_next(&miter)) { > > + while (nbytes && sg_miter_next(&miter)) { > > buff = miter.addr; > > - len = miter.length; > > + len = min_t(unsigned, miter.length, nbytes); > > + nbytes -= len; > > for (x = 0; x < len; x++) { > > a <<= 8; I think it should look like: while (nbytes) { sg_miter_next(&miter); ... } sg_miter_stop(&miter); - Eric