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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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 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 EE305C433ED for ; Wed, 12 May 2021 17:05:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 19D38613AA for ; Wed, 12 May 2021 17:05:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239291AbhELREt (ORCPT ); Wed, 12 May 2021 13:04:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:38450 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238124AbhELP5Y (ORCPT ); Wed, 12 May 2021 11:57:24 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 00AE661CCA; Wed, 12 May 2021 15:30:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1620833424; bh=4v0ba2zeHGtqbuC+LuTU0fkcgKcAJxB8HHhecyZd7kQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=SEu7WjJeA9vnxnMhgcBPphg0hlnfXs21kO5xjU96RNN052aKDelSdzOXBrNqgCykz MmJJfl3vWwwDoI4fPcerQBM3bYD1B5TWk5kXo2tJc9lB3j7hsNELYbIAb474bToQyS b4Dg+NgGgKC5XSnwWvBYYQSA5FyQ79ufIXhcu15M= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Christopherson , Paolo Bonzini Subject: [PATCH 5.11 109/601] KVM: Destroy I/O bus devices on unregister failure _after_ syncing SRCU Date: Wed, 12 May 2021 16:43:06 +0200 Message-Id: <20210512144831.428979450@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210512144827.811958675@linuxfoundation.org> References: <20210512144827.811958675@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sean Christopherson commit 2ee3757424be7c1cd1d0bbfa6db29a7edd82a250 upstream. 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 Message-Id: <20210412222050.876100-2-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- virt/kvm/kvm_main.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4487,7 +4487,13 @@ void kvm_io_bus_unregister_dev(struct kv 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) @@ -4496,8 +4502,6 @@ void kvm_io_bus_unregister_dev(struct kv } } - rcu_assign_pointer(kvm->buses[bus_idx], new_bus); - synchronize_srcu_expedited(&kvm->srcu); kfree(bus); return; }