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=-9.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 23864C433E2 for ; Thu, 3 Sep 2020 17:21:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E31DE20716 for ; Thu, 3 Sep 2020 17:21:38 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="Q+OHpDNc" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728491AbgICRVg (ORCPT ); Thu, 3 Sep 2020 13:21:36 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34520 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726678AbgICRVf (ORCPT ); Thu, 3 Sep 2020 13:21:35 -0400 Received: from mail-pf1-x441.google.com (mail-pf1-x441.google.com [IPv6:2607:f8b0:4864:20::441]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CD5E1C061244; Thu, 3 Sep 2020 10:21:35 -0700 (PDT) Received: by mail-pf1-x441.google.com with SMTP id w7so2866988pfi.4; Thu, 03 Sep 2020 10:21:35 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=WashrslN8ZwCXy2QjOJBW4ZEBVnlFGgH8kdTqqVqsKU=; b=Q+OHpDNczlIeDseieuM5+66rQlgCH+Kn5aoq2pyWKSRq/jsvf4wYVv5KXl5eRtYund JZl5WDBcJ0dEFGAqLKtjWEQjMwWHobhbhirlJ4WtWDrUaVMEscMlOMLfXG+JyNpmjzLY oxFSbjOOweW8JzcG9cIzgdnuw+hZPdguo0goAINeDspq+Hd585n+igQho5kjHNKMnFZs d/mhy+7aWYNhesXOkEhE49hGkccq3nb5j4n/I0AdXXF2vt4g1RiB52gu5KSrMws3Qc7k /uYmO9C9UrVb9wYqhcqsE6TsQgnQ7JmOivOcJy8/ZRep26U1/95AKWQ6rEBBingyaXnA bKKA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=WashrslN8ZwCXy2QjOJBW4ZEBVnlFGgH8kdTqqVqsKU=; b=EneCLvDWfyXI9HSRj/AeuuURaOfFckvN7ggREpZudvB8M9zMUWT2gNfhCVTFjkWO+D ah+74SRFr/lcLKNkHRNDvWm1OY27N1pq3c6tUJ1J3LB81LbvFuUzbwYgo3eqlH3wbmG8 IFHfOdbdwtMijWmMXbUaBkSxJ/aPevEE0eLX+CboG04dgrkTK2a1ITp2UZtGXjNHKP4Y oLpYNeTHHUw4qoq5v4OYaq0P5rOsLLe+odRaWGkKU3+KXWcAi06RXp0spQonzpN+zevk 2ToR7r3hFHpF9zi/kOphe70EdYpWz6OtCvO32aZx55EmJKp5S7dWAAy0B8jrJBoV1rSU qTuQ== X-Gm-Message-State: AOAM533FppvqWe83ZrZWAWlJwTflRxgPUXd7grOf+IMns5xJOJWnfpnx x27F9mXODBIfK66PQfE1pgM= X-Google-Smtp-Source: ABdhPJxr2WeIZr+RTpBi78RWdVAu+wpXA957uq/QJRrasdDFcpqcc/b8n30BnDD45Q8xs6p/dArHuQ== X-Received: by 2002:a62:26c2:: with SMTP id m185mr4764708pfm.115.1599153695177; Thu, 03 Sep 2020 10:21:35 -0700 (PDT) Received: from thinkpad ([2605:8d80:4c0:b73f:202a:aafe:118f:5e94]) by smtp.gmail.com with ESMTPSA id mp3sm3002804pjb.33.2020.09.03.10.21.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 03 Sep 2020 10:21:34 -0700 (PDT) Date: Thu, 3 Sep 2020 10:22:15 -0700 From: Rustam Kovhaev To: "Gustavo A. R. Silva" Cc: pbonzini@redhat.com, vkuznets@redhat.com, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, gregkh@linuxfoundation.org Subject: Re: [PATCH v2] KVM: fix memory leak in kvm_io_bus_unregister_dev() Message-ID: <20200903172215.GA870347@thinkpad> References: <20200902225718.675314-1-rkovhaev@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Sep 02, 2020 at 06:34:11PM -0500, Gustavo A. R. Silva wrote: > Hi, > > On 9/2/20 17:57, Rustam Kovhaev wrote: > > 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 > > Reviewed-by: Vitaly Kuznetsov > > I think it's worthwhile to add a Fixes tag for this, too. > > Please, see more comments below... > > > --- > > v2: > > - remove redundant whitespace > > - remove goto statement and use if/else > > --- > > virt/kvm/kvm_main.c | 21 ++++++++++++--------- > > 1 file changed, 12 insertions(+), 9 deletions(-) > > > > diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c > > index 67cd0b88a6b6..cf88233b819a 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); > > @@ -4349,17 +4349,20 @@ void kvm_io_bus_unregister_dev(struct kvm *kvm, enum kvm_bus bus_idx, > > > > new_bus = kmalloc(struct_size(bus, range, bus->dev_count - 1), > > GFP_KERNEL_ACCOUNT); > > - if (!new_bus) { > > + if (new_bus) { > > + memcpy(new_bus, bus, sizeof(*bus) + i * sizeof(struct kvm_io_range)); > > ^^^ > It seems that you can use struct_size() here (see the allocation code above)... > > > + new_bus->dev_count--; > > + memcpy(new_bus->range + i, bus->range + i + 1, > > + (new_bus->dev_count - i) * sizeof(struct kvm_io_range)); > > ^^^ > ...and, if possible, you can also use flex_array_size() here. > > Thanks > -- > Gustavo > > > + } else { > > pr_err("kvm: failed to shrink bus, removing it completely\n"); > > - goto broken; > > + for (j = 0; j < bus->dev_count; j++) { > > + if (j == i) > > + continue; > > + kvm_iodevice_destructor(bus->range[j].dev); > > + } > > } > > > > - 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)); > > - > > -broken: > > rcu_assign_pointer(kvm->buses[bus_idx], new_bus); > > synchronize_srcu_expedited(&kvm->srcu); > > kfree(bus); > > hi Gustavo, thank you for the review, i'll send the new patch. Vitaly, i think i will need to drop your "Reviewed-by", because there is going to be a bit more changes