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=-26.3 required=3.0 tests=BAYES_00,DKIMWL_WL_MED, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT,USER_IN_DEF_DKIM_WL 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 AED79C433B4 for ; Mon, 12 Apr 2021 22:20:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 88C5C61355 for ; Mon, 12 Apr 2021 22:20:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343690AbhDLWVR (ORCPT ); Mon, 12 Apr 2021 18:21:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45632 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343679AbhDLWVP (ORCPT ); Mon, 12 Apr 2021 18:21:15 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F0CA4C061756 for ; Mon, 12 Apr 2021 15:20:56 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id n13so14114225ybp.14 for ; Mon, 12 Apr 2021 15:20:56 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=reply-to:date:in-reply-to:message-id:mime-version:references :subject:from:to:cc; bh=CWYLK1Nq956lXK6/CZyqJrTCFyW3FBgUwDisoyLnoZE=; b=JAJOXTeFhWLgvXICg+LDvObGR5FL/FNB/jnOfdao44BEDtwrf2fTtD5Z/B54TyJuvX f1m6IQUxQ2aKUsN94lnQWCqu0sUeG96gXdlcegV5bn/XXC3dw3nDZfING2MtRD75cZ3w qYyHV/nZZ03WqXdRKUz6oVzcUTiXUdZck/6yTI+lOjFyA00EjBqJqZSY4p5I8IxXTRnU 45PFjbzpcYriIeK1vtUmjM0IR6Rl2fGlxE4tJGMzBCLeyTQZldelPq1wlsGTwXtlLl8w Yc6sEDtkNLqS+krwgsLIh3nByT9Vv94t8B64o/uyFxDIA2+o2QRMV1rHA/NbJH8WY/7E MlvQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:reply-to:date:in-reply-to:message-id :mime-version:references:subject:from:to:cc; bh=CWYLK1Nq956lXK6/CZyqJrTCFyW3FBgUwDisoyLnoZE=; b=nT+fF9CwkLw5jPNSkp8k1Jnl4Achk8RyR/1i2npI7qh7GOhgpRk8xKnCejTuHVc4uR KyCgr1EMdn6ZfWxZO1hKgnh9Ep/ccl3gtc1/vwxwC++HepLxKm59sYbOQCaAqlntVIyY c76car2pEGCGTFXypDoCBfi7LnGhH3yd7krnHlpL7/nV8duoBaU740p9LIFXa+/g8arX wXopq9M+l9ALbK1bBlnAWQNGnkk9NnLQv5FU8Llm3v8xoAKLN8Vo7MBBRqGsVUPlnhDf 1igbwnEBu5Fqttfjf8EXUC5vSeAPNhMnSIq/6n662clK+f5AqGkPcuTrZiD89AcL30P3 YJlQ== X-Gm-Message-State: AOAM533saOoAav7qyUkgLzAX/snmIqQxKsQtOryqECqrC5f5N9QSYgta OxaJQ8bMnv+HTrfYX/Mao2bg65Ly8/Y= X-Google-Smtp-Source: ABdhPJwIxmb+XLWgx2RW89d77jd3AkTM4I4lGPEqIzhsdt9VwOq9Ll4tWQyfrDSEqTTpMdlUCP0VUNzutpU= X-Received: from seanjc798194.pdx.corp.google.com ([2620:15c:f:10:f031:9c1c:56c7:c3bf]) (user=seanjc job=sendgmr) by 2002:a25:cc3:: with SMTP id 186mr40287194ybm.178.1618266056256; Mon, 12 Apr 2021 15:20:56 -0700 (PDT) Reply-To: Sean Christopherson Date: Mon, 12 Apr 2021 15:20:48 -0700 In-Reply-To: <20210412222050.876100-1-seanjc@google.com> Message-Id: <20210412222050.876100-2-seanjc@google.com> Mime-Version: 1.0 References: <20210412222050.876100-1-seanjc@google.com> X-Mailer: git-send-email 2.31.1.295.g9ea45b61b8-goog Subject: [PATCH 1/3] KVM: Destroy I/O bus devices on unregister failure _after_ sync'ing SRCU From: Sean Christopherson To: Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Sean Christopherson , Hao Sun Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If allocating a new instance of an I/O bus fails when unregistering a device, wait to destroy the device until after all readers are guaranteed to see the new null bus. Destroying devices before the bus is nullified could lead to use-after-free since readers expect the devices on their reference of the bus to remain valid. Fixes: f65886606c2d ("KVM: fix memory leak in kvm_io_bus_unregister_dev()") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson --- virt/kvm/kvm_main.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 383df23514b9..d6e2b570e430 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4511,7 +4511,13 @@ void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, new_bus->dev_count--; memcpy(new_bus->range + i, bus->range + i + 1, flex_array_size(new_bus, range, new_bus->dev_count - i)); - } else { + } + + rcu_assign_pointer(kvm->buses[bus_idx], new_bus); + synchronize_srcu_expedited(&kvm->srcu); + + /* Destroy the old bus _after_ installing the (null) bus. */ + if (!new_bus) { pr_err("kvm: failed to shrink bus, removing it completely\n"); for (j = 0; j < bus->dev_count; j++) { if (j == i) @@ -4520,8 +4526,6 @@ void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, } } - rcu_assign_pointer(kvm->buses[bus_idx], new_bus); - synchronize_srcu_expedited(&kvm->srcu); kfree(bus); return; } -- 2.31.1.295.g9ea45b61b8-goog