From patchwork Wed Aug 24 11:08:45 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Fiona Ebner X-Patchwork-Id: 12953316 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 1370AC00140 for ; Wed, 24 Aug 2022 11:58:08 +0000 (UTC) Received: from localhost ([::1]:45484 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1oQp1L-0000eM-6e for qemu-devel@archiver.kernel.org; Wed, 24 Aug 2022 07:58:07 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]:59500) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oQoGs-0003fD-7j for qemu-devel@nongnu.org; Wed, 24 Aug 2022 07:10:06 -0400 Received: from proxmox-new.maurer-it.com ([94.136.29.106]:5923) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1oQoGj-0006wW-GL for qemu-devel@nongnu.org; Wed, 24 Aug 2022 07:10:05 -0400 Received: from proxmox-new.maurer-it.com (localhost.localdomain [127.0.0.1]) by proxmox-new.maurer-it.com (Proxmox) with ESMTP id 616E343329; Wed, 24 Aug 2022 13:09:43 +0200 (CEST) From: Fiona Ebner To: qemu-devel@nongnu.org Cc: dmitry.fleytman@gmail.com, jasowang@redhat.com, pjp@fedoraproject.org Subject: [RFC] hw/net/vmxnet3: allow VMXNET3_MAX_MTU itself as a value Date: Wed, 24 Aug 2022 13:08:45 +0200 Message-Id: <20220824110845.353435-1-f.ebner@proxmox.com> X-Mailer: git-send-email 2.30.2 MIME-Version: 1.0 Received-SPF: pass client-ip=94.136.29.106; envelope-from=f.ebner@proxmox.com; helo=proxmox-new.maurer-it.com X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" Fixes: d05dcd94ae ("net: vmxnet3: validate configuration values during activate (CVE-2021-20203)") Signed-off-by: Fiona Ebner --- I'm not familiar with this code, so really I'm asking: is the change justified? I tested the change and it seems to work, but I only have some rough rationale for it, which is also why there's no commit message yet. In the Linux kernel's net/core/dev.c, in dev_validate_mtu(), the upper limit itself is a valid value: if (dev->max_mtu > 0 && new_mtu > dev->max_mtu) { NL_SET_ERR_MSG(extack, "mtu greater than device maximum"); return -EINVAL; } and AFAICT in the case of the vmxnet3 driver, max_mtu is set to VMXNET3_MAX_MTU (as defined in the kernel, which is 9000, same as in QEMU). Reported by one of our users running into the failing assert(): https://forum.proxmox.com/threads/114011/#post-492916 hw/net/vmxnet3.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/net/vmxnet3.c b/hw/net/vmxnet3.c index 0b7acf7f89..a2037583bf 100644 --- a/hw/net/vmxnet3.c +++ b/hw/net/vmxnet3.c @@ -1441,7 +1441,7 @@ static void vmxnet3_activate_device(VMXNET3State *s) vmxnet3_setup_rx_filtering(s); /* Cache fields from shared memory */ s->mtu = VMXNET3_READ_DRV_SHARED32(d, s->drv_shmem, devRead.misc.mtu); - assert(VMXNET3_MIN_MTU <= s->mtu && s->mtu < VMXNET3_MAX_MTU); + assert(VMXNET3_MIN_MTU <= s->mtu && s->mtu <= VMXNET3_MAX_MTU); VMW_CFPRN("MTU is %u", s->mtu); s->max_rx_frags =