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 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 smtp.lore.kernel.org (Postfix) with ESMTPS id 4A40FCCF9E9 for ; Wed, 29 Oct 2025 12:22:26 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1vE5BN-0006KO-5P; Wed, 29 Oct 2025 08:21:41 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vE5Az-0006GI-FZ for qemu-devel@nongnu.org; Wed, 29 Oct 2025 08:21:22 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1vE5Am-0007RP-8M for qemu-devel@nongnu.org; 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Wed, 29 Oct 2025 12:20:48 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.72]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 5193B195DD80; Wed, 29 Oct 2025 12:20:46 +0000 (UTC) Date: Wed, 29 Oct 2025 12:20:42 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Peter Maydell Cc: qemu-devel@nongnu.org, Jason Wang , Bin Meng Subject: Re: [PATCH] net: pad packets to minimum length in qemu_receive_packet() Message-ID: References: <20251028160042.3321933-1-peter.maydell@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20251028160042.3321933-1-peter.maydell@linaro.org> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_PASS=-0.001, T_SPF_TEMPERROR=0.01 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Tue, Oct 28, 2025 at 04:00:42PM +0000, Peter Maydell wrote: > In commits like 969e50b61a28 ("net: Pad short frames to minimum size > before sending from SLiRP/TAP") we switched away from requiring > network devices to handle short frames to instead having the net core > code do the padding of short frames out to the ETH_ZLEN minimum size. > We then dropped the code for handling short frames from the network > devices in a series of commits like 140eae9c8f7 ("hw/net: e1000: > Remove the logic of padding short frames in the receive path"). > > This missed one route where the device's receive code can still see a > short frame: if the device is in loopback mode and it transmits a > short frame via the qemu_receive_packet() function, this will be fed > back into its own receive code without being padded. > > Add the padding logic to qemu_receive_packet(). > > This fixes a buffer overrun which can be triggered in the > e1000_receive_iov() logic via the loopback code path. > > Other devices that use qemu_receive_packet() to implement loopback > are cadence_gem, dp8393x, lan9118, msf2-emac, pcnet, rtl8139 > and sungem. > > Cc: qemu-stable@nongnu.org > Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3043 > Signed-off-by: Peter Maydell Since it is guest triggerable, this bug has been assigned CVE-2025-12464 > --- > I think this is the right fix, but I'm not very familiar > with the net internals... > --- > net/net.c | 10 ++++++++++ > 1 file changed, 10 insertions(+) With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|