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 X-Spam-Level: X-Spam-Status: No, score=-17.6 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6C4FBC433F5 for ; Tue, 7 Sep 2021 13:58:21 +0000 (UTC) Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id AF8B160F43 for ; Tue, 7 Sep 2021 13:58:20 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org AF8B160F43 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=proxmox.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=nongnu.org Received: from localhost ([::1]:60792 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1mNbcB-00067p-Tc for qemu-devel@archiver.kernel.org; Tue, 07 Sep 2021 09:58:19 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:41936) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mNb0o-0004Ji-CV; Tue, 07 Sep 2021 09:19:42 -0400 Received: from proxmox-new.maurer-it.com ([94.136.29.106]:62609) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1mNb0l-0004M0-U6; Tue, 07 Sep 2021 09:19:41 -0400 Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id D1FCB445F7; Tue, 7 Sep 2021 15:19:28 +0200 (CEST) Subject: Re: [PATCH v3] qemu-sockets: fix unix socket path copy (again) To: Michael Tokarev , qemu-devel@nongnu.org References: <20210901131624.46171-1-mjt@msgid.tls.msk.ru> From: Stefan Reiter Message-ID: <4f9e8064-c346-3c54-fa94-1b6a641f9971@proxmox.com> Date: Tue, 7 Sep 2021 15:19:27 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <20210901131624.46171-1-mjt@msgid.tls.msk.ru> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=94.136.29.106; envelope-from=s.reiter@proxmox.com; helo=proxmox-new.maurer-it.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, NICE_REPLY_A=-2.332, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: =?UTF-8?Q?Marc-Andr=c3=a9_Lureau?= , =?UTF-8?Q?Daniel_P_=2e_Berrang=c3=a9?= , qemu-stable@nongnu.org, Peter Maydell Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Thanks for the patch, ran into the same issue here and was about to send my own ;) On 9/1/21 3:16 PM, Michael Tokarev wrote: > Commit 4cfd970ec188558daa6214f26203fe553fb1e01f added an > assert which ensures the path within an address of a unix > socket returned from the kernel is at least one byte and > does not exceed sun_path buffer. Both of this constraints > are wrong: > > A unix socket can be unnamed, in this case the path is > completely empty (not even \0) > > And some implementations (notable linux) can add extra > trailing byte (\0) _after_ the sun_path buffer if we > passed buffer larger than it (and we do). > > So remove the assertion (since it causes real-life breakage) > but at the same time fix the usage of sun_path. Namely, > we should not access sun_path[0] if kernel did not return > it at all (this is the case for unnamed sockets), > and use the returned salen when copyig actual path as an > upper constraint for the amount of bytes to copy - this > will ensure we wont exceed the information provided by > the kernel, regardless whenever there is a trailing \0 > or not. This also helps with unnamed sockets. > > Note the case of abstract socket, the sun_path is actually > a blob and can contain \0 characters, - it should not be > passed to g_strndup and the like, it should be accessed by > memcpy-like functions. I know this is already applied now, but I noticed that you don't actually follow through on that part - g_strndup is still used in both cases for sun_path. Haven't run into a bug with this, just noting that the commit message is a bit confusing paired with the patch. Might be a bit tricky though, as all callers would need to be careful too... > > Fixes: 4cfd970ec188558daa6214f26203fe553fb1e01f > Fixes: http://bugs.debian.org/993145 > Signed-off-by: Michael Tokarev > CC: qemu-stable@nongnu.org > --- > util/qemu-sockets.c | 13 +++++-------- > 1 file changed, 5 insertions(+), 8 deletions(-) > > diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c > index f2f3676d1f..c5043999e9 100644 > --- a/util/qemu-sockets.c > +++ b/util/qemu-sockets.c > @@ -1345,25 +1345,22 @@ socket_sockaddr_to_address_unix(struct sockaddr_storage *sa, > SocketAddress *addr; > struct sockaddr_un *su = (struct sockaddr_un *)sa; > > - assert(salen >= sizeof(su->sun_family) + 1 && > - salen <= sizeof(struct sockaddr_un)); > - > addr = g_new0(SocketAddress, 1); > addr->type = SOCKET_ADDRESS_TYPE_UNIX; > + salen -= offsetof(struct sockaddr_un, sun_path); > #ifdef CONFIG_LINUX > - if (!su->sun_path[0]) { > + if (salen > 0 && !su->sun_path[0]) { > /* Linux abstract socket */ > - addr->u.q_unix.path = g_strndup(su->sun_path + 1, > - salen - sizeof(su->sun_family) - 1); > + addr->u.q_unix.path = g_strndup(su->sun_path + 1, salen - 1); > addr->u.q_unix.has_abstract = true; > addr->u.q_unix.abstract = true; > addr->u.q_unix.has_tight = true; > - addr->u.q_unix.tight = salen < sizeof(*su); > + addr->u.q_unix.tight = salen < sizeof(su->sun_path); > return addr; > } > #endif > > - addr->u.q_unix.path = g_strndup(su->sun_path, sizeof(su->sun_path)); > + addr->u.q_unix.path = g_strndup(su->sun_path, salen); > return addr; > } > #endif /* WIN32 */ >