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 15CE2F46112 for ; Mon, 23 Mar 2026 13:43:16 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1w4fXl-0006I5-6A; Mon, 23 Mar 2026 09:42:09 -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 1w4fXf-0006Gp-Vm for qemu-devel@nongnu.org; Mon, 23 Mar 2026 09:42:04 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1w4fXa-0004Em-CM for qemu-devel@nongnu.org; Mon, 23 Mar 2026 09:42:02 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1774273316; h=from:from:reply-to: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=FFR/uvyPyMIgIXD2fn4+1E5+IwSBm0k0CtQI5ytOBHM=; b=Gie/ahJLmVuvXCq/TOop9R9BbqYVHafklttFtUn3RAXEk28Rr/HES/kLBIaj2QvrmmY8nZ +qg6hujtCfIavMWnjVRmoHbwMP9ZT6SIwIGGlcynadTCxub8B5c6754ldq82uVm3Nxsrk1 A1o71T/67khuDcgwRy93mJSw5eZq+L4= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-183-El3kUb4KNFm2U59OrEaHeg-1; Mon, 23 Mar 2026 09:41:52 -0400 X-MC-Unique: El3kUb4KNFm2U59OrEaHeg-1 X-Mimecast-MFC-AGG-ID: El3kUb4KNFm2U59OrEaHeg_1774273306 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 79FA51955DDB; Mon, 23 Mar 2026 13:41:46 +0000 (UTC) Received: from redhat.com (unknown [10.45.224.227]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id BAD1B300019F; Mon, 23 Mar 2026 13:41:43 +0000 (UTC) Date: Mon, 23 Mar 2026 13:41:40 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Junjie Cao Cc: qemu-devel@nongnu.org, jasowang@redhat.com, mst@redhat.com, yuri.benditovich@daynix.com, akihiko.odaki@daynix.com, qemu-stable@nongnu.org Subject: Re: [PATCH] virtio-net: validate RSS indirections_len in post_load Message-ID: References: <20260323131531.1976-1-junjie.cao@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20260323131531.1976-1-junjie.cao@intel.com> User-Agent: Mutt/2.2.14 (2025-02-20) X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 Received-SPF: pass client-ip=170.10.129.124; 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, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development 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 Mon, Mar 23, 2026 at 09:15:31PM +0800, Junjie Cao wrote: > virtio_net_handle_rss() enforces that indirections_len is a non-zero > power of two no larger than VIRTIO_NET_RSS_MAX_TABLE_LEN, but > virtio_net_rss_post_load() applies none of these checks to values > restored from the migration stream. > > A crafted migration stream can set indirections_len to 0. Even if it The migration stream originating from the source QEMU is trusted. Is there a problem you can demonstrate with regular QEMU commands / versions, not crafting a malicious migration stream. > also clears redirect, virtio_load() calls set_features_nocheck() after > the device vmstate (including the RSS subsection and its post_load) has > already been loaded, re-deriving redirect from the negotiated guest > features. When VIRTIO_NET_F_RSS was negotiated, redirect is set back > to true regardless of the migration stream value. The receive path > then computes > > hash & (indirections_len - 1) /* wraps to 0xFFFFFFFF via int promotion */ > > and uses the result to index into indirections_table, which was not > allocated by the VMState loader when the element count is zero (see > vmstate_handle_alloc()), resulting in a NULL pointer dereference that > crashes QEMU: > > #0 virtio_net_process_rss ../hw/net/virtio-net.c:1901 > #1 virtio_net_receive_rcu ../hw/net/virtio-net.c:1921 > #2 virtio_net_do_receive ../hw/net/virtio-net.c:2061 > #3 nc_sendv_compat ../net/net.c:823 > #4 qemu_deliver_packet_iov ../net/net.c:870 > > The RSS subsection is only loaded when rss_data.enabled is true (via > virtio_net_rss_needed()), and the command path always produces > indirections_len in {1, 2, 4, …, 128}, so an unconditional check > cannot reject a legitimate migration stream. > > Fixes: e41b711485e5 ("virtio-net: add migration support for RSS and hash report") > Cc: qemu-stable@nongnu.org > Signed-off-by: Junjie Cao > --- > hw/net/virtio-net.c | 9 +++++++++ > 1 file changed, 9 insertions(+) > > diff --git a/hw/net/virtio-net.c b/hw/net/virtio-net.c > index 2a5d642a64..3038836098 100644 > --- a/hw/net/virtio-net.c > +++ b/hw/net/virtio-net.c > @@ -3427,6 +3427,15 @@ static int virtio_net_rss_post_load(void *opaque, int version_id) > n->rss_data.supported_hash_types = VIRTIO_NET_RSS_SUPPORTED_HASHES; > } > > + if (n->rss_data.indirections_len == 0 || > + n->rss_data.indirections_len > VIRTIO_NET_RSS_MAX_TABLE_LEN || > + !is_power_of_2(n->rss_data.indirections_len)) { > + error_report("virtio-net: saved image has invalid RSS " > + "indirections_len: %u", > + n->rss_data.indirections_len); > + return -EINVAL; > + } > + > return 0; > } > > -- > 2.43.0 > > With regards, Daniel -- |: https://berrange.com ~~ https://hachyderm.io/@berrange :| |: https://libvirt.org ~~ https://entangle-photo.org :| |: https://pixelfed.art/berrange ~~ https://fstop138.berrange.com :|