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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 6C416C4332B for ; Wed, 24 Feb 2021 13:50:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3523264F09 for ; Wed, 24 Feb 2021 13:50:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237752AbhBXNrC (ORCPT ); Wed, 24 Feb 2021 08:47:02 -0500 Received: from mail.kernel.org ([198.145.29.99]:59130 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233136AbhBXNKj (ORCPT ); Wed, 24 Feb 2021 08:10:39 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id DD2DD64F11; Wed, 24 Feb 2021 12:55:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614171302; bh=8vUotaZ9PS8Rw6qxPntNdQtu1ucj2oPPA0Ltl1E0x7M=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=ix82ElRvHjEgkpeDWflNuItG1cxHOPihLPRJMtwfrLzqOj1HlTQ5xmQi8xR4/a9Ny 8RJBg7PiH77AzZdRf9Q8+6m7kl5lhcAkBAki3uF6pgnxvJSeMAkMfGCWT9xal9BHDb 6rcOLTrwVHIdKS4jd+FVRRSMRZiY/kllNxnUicve87roADKT1digO81P5W4gtbhslU SshuyDB3YSITgoUNlU57Prmwew29z+ZFCCHPxxFoJ8lZOlJcTBoEGCBppboCV+F1pD asTC6QNxL3q5la5kPbvIoA/OJpIbaIpm2QsBriKGGGiGKSLRhZBNWuNmjFQUJrMmwF WlBnLEJlOdbMA== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: "Andrea Parri (Microsoft)" , Juan Vazquez , Michael Kelley , Wei Liu , Sasha Levin , linux-hyperv@vger.kernel.org Subject: [PATCH AUTOSEL 4.19 21/26] Drivers: hv: vmbus: Resolve race condition in vmbus_onoffer_rescind() Date: Wed, 24 Feb 2021 07:54:29 -0500 Message-Id: <20210224125435.483539-21-sashal@kernel.org> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210224125435.483539-1-sashal@kernel.org> References: <20210224125435.483539-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-hyperv@vger.kernel.org From: "Andrea Parri (Microsoft)" [ Upstream commit e4d221b42354b2e2ddb9187a806afb651eee2cda ] An erroneous or malicious host could send multiple rescind messages for a same channel. In vmbus_onoffer_rescind(), the guest maps the channel ID to obtain a pointer to the channel object and it eventually releases such object and associated data. The host could time rescind messages and lead to an use-after-free. Add a new flag to the channel structure to make sure that only one instance of vmbus_onoffer_rescind() can get the reference to the channel object. Reported-by: Juan Vazquez Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Michael Kelley Link: https://lore.kernel.org/r/20201209070827.29335-6-parri.andrea@gmail.com Signed-off-by: Wei Liu Signed-off-by: Sasha Levin --- drivers/hv/channel_mgmt.c | 12 ++++++++++++ include/linux/hyperv.h | 1 + 2 files changed, 13 insertions(+) diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c index 7920b0d7e35a7..1322e799938af 100644 --- a/drivers/hv/channel_mgmt.c +++ b/drivers/hv/channel_mgmt.c @@ -954,6 +954,18 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr) mutex_lock(&vmbus_connection.channel_mutex); channel = relid2channel(rescind->child_relid); + if (channel != NULL) { + /* + * Guarantee that no other instance of vmbus_onoffer_rescind() + * has got a reference to the channel object. Synchronize on + * &vmbus_connection.channel_mutex. + */ + if (channel->rescind_ref) { + mutex_unlock(&vmbus_connection.channel_mutex); + return; + } + channel->rescind_ref = true; + } mutex_unlock(&vmbus_connection.channel_mutex); if (channel == NULL) { diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h index 35461d49d3aee..59525fe25abde 100644 --- a/include/linux/hyperv.h +++ b/include/linux/hyperv.h @@ -736,6 +736,7 @@ struct vmbus_channel { u8 monitor_bit; bool rescind; /* got rescind msg */ + bool rescind_ref; /* got rescind msg, got channel reference */ struct completion rescind_event; u32 ringbuffer_gpadlhandle; -- 2.27.0