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=-13.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 19307C433B4 for ; Wed, 12 May 2021 10:46:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D045661183 for ; Wed, 12 May 2021 10:46:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230224AbhELKrx (ORCPT ); Wed, 12 May 2021 06:47:53 -0400 Received: from wforward4-smtp.messagingengine.com ([64.147.123.34]:47677 "EHLO wforward4-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230185AbhELKrx (ORCPT ); Wed, 12 May 2021 06:47:53 -0400 Received: from compute4.internal (compute4.nyi.internal [10.202.2.44]) by mailforward.west.internal (Postfix) with ESMTP id 8C82C12DF; Wed, 12 May 2021 06:46:44 -0400 (EDT) Received: from mailfrontend2 ([10.202.2.163]) by compute4.internal (MEProxy); Wed, 12 May 2021 06:46:44 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=GiAhWE oZkrPYsKnVxhcO8vCQvsDVr1qrWZbsOteoNVU=; b=UmMEthj5XkWCaw3XPVHClT SwbgyCw5RC7I25JX0DOF37G9KoVP1pnUzTJzIiGHYWiBh6qtzFgW06VZOLlKl8Th xDSeF3HeQvQYyY7m08qtHZDc/MeJiRHgSOJelCktESZL4mLtmMfFt88NztdRcCqD KGOlZ4lnMcMlqqGTi2kSGem6GMNqqlMyGj87vjfJA8UE/tn26FIhKA49Epvti4j3 3DEJfZfMWut22TPtbDbc0w3LBwAAGzAYpLfGhhLA4skeAuAhNyRPeIWiWNJyvfXX CGfJpFxKt8yd7kUNxm96s0fj3gdHeBC8ZkB4PunFzcAywRHZJx+sgonvm2jTFzUg == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgeduledrvdehvddgvdelucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucenucfjughrpefuvffhfffkgggtgfesthekredttd dtlfenucfhrhhomhepoehgrhgvghhkhheslhhinhhugihfohhunhgurghtihhonhdrohhr gheqnecuggftrfgrthhtvghrnhepieetveehuedvhfdtgfdvieeiheehfeelveevheejud etveeuveeludejjefgteehnecukfhppeekfedrkeeirdejgedrieegnecuvehluhhsthgv rhfuihiivgepieenucfrrghrrghmpehmrghilhhfrhhomhepghhrvghgsehkrhhorghhrd gtohhm X-ME-Proxy: Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) by mail.messagingengine.com (Postfix) with ESMTPA; Wed, 12 May 2021 06:46:43 -0400 (EDT) Subject: FAILED: patch "[PATCH] KVM: Destroy I/O bus devices on unregister failure _after_" failed to apply to 4.4-stable tree To: seanjc@google.com, pbonzini@redhat.com Cc: From: Date: Wed, 12 May 2021 12:46:42 +0200 Message-ID: <162081640272133@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 2ee3757424be7c1cd1d0bbfa6db29a7edd82a250 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Mon, 12 Apr 2021 15:20:48 -0700 Subject: [PATCH] KVM: Destroy I/O bus devices on unregister failure _after_ sync'ing SRCU 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 diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c index 529cff1050d7..c771d40737c9 100644 --- a/virt/kvm/kvm_main.c +++ b/virt/kvm/kvm_main.c @@ -4646,7 +4646,13 @@ 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) @@ -4655,8 +4661,6 @@ 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; }