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=-10.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED 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 33C36C433E6 for ; Tue, 1 Sep 2020 16:25:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 12BC4208CA for ; Tue, 1 Sep 2020 16:25:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="Z714eEeB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731860AbgIAQZ5 (ORCPT ); Tue, 1 Sep 2020 12:25:57 -0400 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:23376 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1732083AbgIAQZv (ORCPT ); Tue, 1 Sep 2020 12:25:51 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1598977550; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=02QkjKG1ciVZ/SZ1+fSg/UxfgUofnVY9E0gaoJNRSe8=; b=Z714eEeB82E3pQf2DqnrmDZ3EjX4Ue8oYMhZs4IKwfnPJcPLd03BuknMy7eGD/xsPyKx9i lwVzC8hhtnAmCmvv7LtU0VUzk2nwgO2kHlcCsBuBfjv/4h/ukefxIXVxjlsT5KswF4AsL3 1WQMH+4rqzugNHDdxP4rXCn3wuxJd4E= Received: from mail-wr1-f72.google.com (mail-wr1-f72.google.com [209.85.221.72]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-391-rk76fVWmMOy8sP2L9sIy4g-1; Tue, 01 Sep 2020 12:25:46 -0400 X-MC-Unique: rk76fVWmMOy8sP2L9sIy4g-1 Received: by mail-wr1-f72.google.com with SMTP id e14so779670wrr.7 for ; Tue, 01 Sep 2020 09:25:46 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:in-reply-to:references:date :message-id:mime-version; bh=02QkjKG1ciVZ/SZ1+fSg/UxfgUofnVY9E0gaoJNRSe8=; b=fpUNiT7kIvq9BoClKZ/LC1Gx2/mIluba3YjR7jezssW+D3QcjnQ1SHMBJa/bcsCg1p b1uPTUALhAqS3utzjCSCbVVzy9yvcj4hWz/1TTIjkRkswh2KS68rYXhvpXX6zssMWvGd Lfbfa3fgGhzOQ1wvhmiKYb+FiNGWvpaOdt74OCj4ND9QxF6BlkqYTvAaPwxvgVE9aLR0 qVN3tDqdYRacU8t2LRIfiF6rqhhH1Z6pX4x/JuLfU04O2rNHo5W+Wf/SiLoL1dGXXEim OjdqYB1UnlNvKROpVDGy9RWebqIbdJn9GbcP88uXbexG2P39Ea5LVGXYocUYJR+Dv+jH 8dug== X-Gm-Message-State: AOAM532ziTU3MEWCpcFblHIqRVtUazvOzZP/ePNaLVCHGPMdbLv6wtfP VkRUbTp75jImPGN59XGPaYf4P7N/u83TBWBghVpVNiqUwow8BUMG5MsNydbaPYJubyuuQA3HyUz uoRF77+s1b99s X-Received: by 2002:adf:e8c3:: with SMTP id k3mr2794204wrn.228.1598977544740; Tue, 01 Sep 2020 09:25:44 -0700 (PDT) X-Google-Smtp-Source: ABdhPJwZBwMu9jEZcrJ5aoeYibQLoi7inHjh994XlsUOFj/MJ/rDb4MiJy+fC4tFpUaP66vXk9YJmg== X-Received: by 2002:adf:e8c3:: with SMTP id k3mr2794187wrn.228.1598977544552; Tue, 01 Sep 2020 09:25:44 -0700 (PDT) Received: from vitty.brq.redhat.com (g-server-2.ign.cz. [91.219.240.2]) by smtp.gmail.com with ESMTPSA id d11sm3116525wrw.77.2020.09.01.09.25.42 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Sep 2020 09:25:43 -0700 (PDT) From: Vitaly Kuznetsov To: Rustam Kovhaev Cc: linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org, pbonzini@redhat.com, kvm@vger.kernel.org Subject: Re: [PATCH] KVM: fix memory leak in kvm_io_bus_unregister_dev() In-Reply-To: <20200830043405.268044-1-rkovhaev@gmail.com> References: <20200830043405.268044-1-rkovhaev@gmail.com> Date: Tue, 01 Sep 2020 18:25:42 +0200 Message-ID: <877dtdwjjt.fsf@vitty.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org Rustam Kovhaev writes: > when kmalloc() fails in kvm_io_bus_unregister_dev(), before removing > the bus, we should iterate over all other devices linked to it and call > kvm_iodevice_destructor() for them > > Reported-and-tested-by: syzbot+f196caa45793d6374707@syzkaller.appspotmail.com > Link: https://syzkaller.appspot.com/bug?extid=f196caa45793d6374707 > Signed-off-by: Rustam Kovhaev > --- > virt/kvm/kvm_main.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > index 67cd0b88a6b6..646aa7b82548 100644 > --- a/virt/kvm/kvm_main.c > +++ b/virt/kvm/kvm_main.c > @@ -4332,7 +4332,7 @@ int kvm_io_bus_register_dev(struct kvm *kvm, enum kvm_bus bus_idx, gpa_t addr, > void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, > struct kvm_io_device *dev) > { > - int i; > + int i, j; > struct kvm_io_bus *new_bus, *bus; > > bus = kvm_get_bus(kvm, bus_idx); > @@ -4351,6 +4351,11 @@ void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, > GFP_KERNEL_ACCOUNT); > if (!new_bus) { ^^^ redundant space > pr_err("kvm: failed to shrink bus, removing it completely\n"); > + for (j = 0; j < bus->dev_count; j++) { > + if (j == i) > + continue; > + kvm_iodevice_destructor(bus->range[j].dev); > + } > goto broken; The name of the label is really misleading (as it is not actually a failure path), I'd even suggest we get rid of this goto completely, something like new_bus = kmalloc(struct_size(bus, range, bus->dev_count - 1), GFP_KERNEL_ACCOUNT); if (new_bus) { memcpy(new_bus, bus, sizeof(*bus) + i * sizeof(struct kvm_io_range)); new_bus->dev_count--; memcpy(new_bus->range + i, bus->range + i + 1, (new_bus->dev_count - i) * sizeof(struct kvm_io_range)); } else { pr_err("kvm: failed to shrink bus, removing it completely\n"); for (j = 0; j < bus->dev_count; j++) { if (j == i) continue; kvm_iodevice_destructor(bus->range[j].dev); } rcu_assign_pointer(kvm->buses[bus_idx], new_bus); synchronize_srcu_expedited(&kvm->srcu); kfree(bus); return; > } None of the above should block the fix IMO, so: Reviewed-by: Vitaly Kuznetsov -- Vitaly