From nobody Thu Sep 12 09:40:26 2024 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4X4C975v34z5Vytp; Thu, 12 Sep 2024 09:40:27 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [IPv6:2610:1c1:1:606c::24b:4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "R10" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4X4C975RxCz4mJH; Thu, 12 Sep 2024 09:40:27 +0000 (UTC) (envelope-from jhb@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1726134027; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=94I1LuW0beh9DG/KCey7Y+9ELYSr0YPe8V6krnElkx8=; b=U8mNf3RAfdpbxSLYBnSt+U0WWjZxKBSg4M7Q3mbiDOQxdzFUdVmeZ7hNyuGVg+FCOE9UKY GABIC1cZbYWIa2lczGziMxfksA83itQ3yi9krM9Jfffe+93etA+WCqHkpLZDJkeb0SLE8b seOUUd1C0YDy2nsTlySTeujzYgU+Q8Q+Qd8PiWelVWXIR+tDM4y7PN5zmBaIFqWP4DlpMZ +7pAJoBf68IYP/t+vcnngv1Fgcw2PX2wRLRltTKpH+lR8ixd6PCuqJvMX8OZy70IeHOdY3 d7UMQeToV1TssJawhluhsUr+hzRxU4DQV1nWuC7XYY+YwOWQZXDhBfcWR5ZjHA== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1726134027; a=rsa-sha256; cv=none; b=Q4pulqX46GURRoauEGCyuUKu9ZIZsLh6dA+u1+o37zWGYXD/V7gL+wVkNIgyqLN+UZLTtN IyUHMY0ngp2wjRjCMnK/j0TRsqvhKnTvJd27TdvPO1r4X0dvIapkcRDpkK2rSe0DkiiGxi WeRSRwQL9XhPkQG4WrTWbxuYr6YqCiLrA0DfqT2swdaeIVSIOYNyAHBDgxLQAW0C1iQ2U4 Y96lUpXQPr5yiK5kAayIS22GKIRJ+lpVKTidFO1m+g+5cmW8JWdkhU2z0H7GPk+HpkVGHA VKr0D6xLGBqQMtEphzVbGsKkomIKXoe35+r88CkSj+wZXABhZbROgcii0Z0yvw== ARC-Authentication-Results: i=1; mx1.freebsd.org; none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1726134027; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=94I1LuW0beh9DG/KCey7Y+9ELYSr0YPe8V6krnElkx8=; b=visNxVnn/2wAbLqv8uB8sgmNsmZQeCUH2RCHs9atYkWJXl+WJo6mA8LiW0ziCcX/4ZKE6r ZWxouyFYY3VDg7um6oRenxQPL2L3ciRtRc+HGmvJUYm35aoeJ9kk330kPSBPJNIwhi7FKZ V5TvU5GATL1SUBv56B/jAI5yhm0nTpqa809z/A5HozIQRIxIa0REFe5wU4o8B4cBeVp0Zm QxiIktbFgIG/S7sfMhONnPX8aJL04cwXfAUIErB4CgCjKaHbDukNuE6bURB11Oubs8diSq oVdbwI9iwpZr8wolu1IP9rcYcMtcYNDQ52gheXdk1/u6IQPlZi1dr6Cc1Mfcvw== Received: from [10.252.223.137] (unknown [131.111.5.201]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) (Authenticated sender: jhb) by smtp.freebsd.org (Postfix) with ESMTPSA id 4X4C970qCczLcH; Thu, 12 Sep 2024 09:40:27 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Message-ID: <1f61b6de-0fe2-4343-b4ad-f0866785a4bc@FreeBSD.org> Date: Thu, 12 Sep 2024 10:40:26 +0100 List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@FreeBSD.org MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: git: f08247fd888e - main - Assert that mbufs are writable if we write to them Content-Language: en-US From: John Baldwin To: Drew Gallatin , Kristof Provost , Mark Johnston Cc: src-committers@freebsd.org, dev-commits-src-all@freebsd.org, dev-commits-src-main@freebsd.org References: <202409111118.48BBIQ2h065089@gitrepo.freebsd.org> <2b1955e2-fbf1-41cb-b256-a9a257b16a83@FreeBSD.org> In-Reply-To: <2b1955e2-fbf1-41cb-b256-a9a257b16a83@FreeBSD.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 9/12/24 05:03, John Baldwin wrote: > I think part of the motivation for marking M_EXTPG as read-only is that you can't "write" > to m_data via mtod() or the like. That said, M_EXTPG aren't really read-only. It > depends on the backing store. M_EXTPG were first merged into FreeBSD prior to KTLS to > support sendfile, and in that case, they should be M_RDONLY because they alias pages > from the file's VM object. However, M_EXTPG mbufs allocated via functions like > m_uiotombuf_nomap should not be M_RDONLY. I think this originated in the original > import of KTLS which doesn't push setting M_RDONLY out to the callers of mb_alloc_extpgs, > and a few other places that hardcode M_RDONLY with M_EXTPG (_mb_unmapped_to_ext should > preserve M_RDONLY from the original mbuf instead of forcing M_RDONLY). > > I can take a stab at a patch but won't have time to really test it until after Euro. Patch available below. Compile tested but not run-tested: https://github.com/freebsd/freebsd-src/compare/main...bsdjhb:freebsd:m_extpg_rdonly > On 9/11/24 16:56, Drew Gallatin wrote: >> M_EXTPGS mbufs are marked read-only because they refer to external data. The original crypto code, (before kTLS was converted to OCF), used to just build an iovec using PHYS_TO_DMAP() on the page array. I think this case was missed during the conversion to OCF. >> >> I'm not sure what the best thing to do is, as they should be read only, except this one specific case.... I'd be tempted to just nerf the KASSERT for EXTPGS. >> >> On Wed, Sep 11, 2024, at 11:02 AM, Kristof Provost wrote: >>> On 11 Sep 2024, at 16:45, Mark Johnston wrote: >>>> On Wed, Sep 11, 2024 at 11:18:26AM +0000, Kristof Provost wrote: >>>>> The branch main has been updated by kp: >>>>> >>>>> URL: https://cgit.FreeBSD.org/src/commit/?id=f08247fd888e6f7db0ecf2aaa39377144ac40b4c >>>>> >>>>> commit f08247fd888e6f7db0ecf2aaa39377144ac40b4c >>>>> Author: Kristof Provost >>>>> AuthorDate: 2024-09-10 20:15:31 +0000 >>>>> Commit: Kristof Provost >>>>> CommitDate: 2024-09-11 11:17:48 +0000 >>>>> >>>>> Assert that mbufs are writable if we write to them >>>>> >>>>> m_copyback() modifies the mbuf, so it must be a writable mbuf. >>>> >>>> This change still triggers a panic for me when running KTLS tests. I >>>> note that EXTPG mbufs always have M_RDONLY set, but I'm not quite sure >>>> why. I suspect such mbufs need special handling with respect to the new >>>> assertion. >>>> >>>> syzbot also triggered this panic: >>>> https://syzkaller.appspot.com/bug?extid=58c918369f9dc323409d >>>> >>> Yeah, I saw that one before I went out for a bike ride. >>> >>> Clearly something is wrong. Either ktls is using read-only buffers or the M_WRITABLE() macro isn’t quite smart enough to spot this specific case. >>> >>> I’m not familiar enough with ktls to easily tell which. >>> >>> I’ll back this assertion change out for now, so we’re not panicing test machines while we figure this out. >>> >>> Best regards, >>> Kristof >>> >> > -- John Baldwin