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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 51F12C4332F for ; Mon, 30 Oct 2023 22:12:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230339AbjJ3WMT (ORCPT ); Mon, 30 Oct 2023 18:12:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:33074 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229682AbjJ3WMR (ORCPT ); Mon, 30 Oct 2023 18:12:17 -0400 Received: from mail-pf1-x44a.google.com (mail-pf1-x44a.google.com [IPv6:2607:f8b0:4864:20::44a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B02B5E8 for ; Mon, 30 Oct 2023 15:12:12 -0700 (PDT) Received: by mail-pf1-x44a.google.com with SMTP id d2e1a72fcca58-6b2018a11e2so5038131b3a.2 for ; Mon, 30 Oct 2023 15:12:12 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1698703932; x=1699308732; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=g8DEvtikhnQyn+T5K55cZjm1cs6/IKtx/WCyiBBil5U=; b=WmJRwsVAjOdugnxCaIdp3UcES2KqSgFbohBM76jKC7YPTZJdwtQ2PJU+QhiSZRiH2N 5grrkTcJsGZVpzmuJiqBvCAH1jTwlEWNQ6KcmVPhvVQu+YoCWBCWzm6bIO9PqhzlbpZp bS6cnQ2aFt/5tjb0yB7qKOY3M/1aFkZWpPMzd1YNkwGkI5BJrTgc2Xx9Eat3tgF88QvR 0KnkZG31xaUlQfT7A+8SN8KfNPxTV7vbtZmhGawVrF4NEf/86WzkrpHQrHqu808T/NsV Hmzh/NgXh85ruWCCmnVbRbrEROpg/OPDFFG1M6s5VPyp+ehahaeFeXgpKRtJp/Y/So0q db0g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1698703932; x=1699308732; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=g8DEvtikhnQyn+T5K55cZjm1cs6/IKtx/WCyiBBil5U=; b=jzhjl9bN7TDRsz2U77MJvB7LBa2NyG2R496xa2fihIN9gNjfuT5eln7HyB32fusD7J CBmbIzzQsntLxaqoUBvcP9kO7yw6/RSJm/oHAzvY1T7w8PCt7BIO+UgpKxmtfBamBsDL MJNzI94oVMEPh1T1QODNNlnf0nQeP2HB9SQj8pPqwFhzO0ILXjDOjtU1DZheLJiUYjOz SBtxie4NoQyAsselAerIHCANw+2XWi+jvbnLilpRi3uvqWLZJcLcZS0LMgoW0iQNLy3/ j7cWN1LqVRw1LskusES1Am5EXrqiM4hiVqiXFUTimlghlABQwLSKRle/A0yLaLhmHLdq 9o9A== X-Gm-Message-State: AOJu0Ywa+tUr3Hw12XVeWRec7xEUjiYk23NUIq7dApkBWooE/53NJ5nR SYouMYK+EKMRQcisWQJALx1U60hxxw8= X-Google-Smtp-Source: AGHT+IGGcxVYGAYGv3uCrE8wHX1TR4p8IURd9gUNgfJNwa+fo9vdIR8HGGPD/6eLST5HVrX+Zf4WM1nECms= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6a00:1755:b0:68e:24fe:d9a with SMTP id j21-20020a056a00175500b0068e24fe0d9amr205380pfc.2.1698703932137; Mon, 30 Oct 2023 15:12:12 -0700 (PDT) Date: Mon, 30 Oct 2023 15:12:10 -0700 In-Reply-To: Mime-Version: 1.0 References: <20231027182217.3615211-1-seanjc@google.com> <20231027182217.3615211-9-seanjc@google.com> <211d093f-4023-4a39-a23f-6d8543512675@redhat.com> Message-ID: Subject: Re: [PATCH v13 08/35] KVM: Introduce KVM_SET_USER_MEMORY_REGION2 From: Sean Christopherson To: Paolo Bonzini Cc: Marc Zyngier , Oliver Upton , Huacai Chen , Michael Ellerman , Anup Patel , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexander Viro , Christian Brauner , "Matthew Wilcox (Oracle)" , Andrew Morton , kvm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, kvmarm@lists.linux.dev, linux-mips@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-riscv@lists.infradead.org, linux-riscv@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, Xiaoyao Li , Xu Yilun , Chao Peng , Fuad Tabba , Jarkko Sakkinen , Anish Moorthy , David Matlack , Yu Zhang , Isaku Yamahata , "=?utf-8?Q?Micka=C3=ABl_Sala=C3=BCn?=" , Vlastimil Babka , Vishal Annapurve , Ackerley Tng , Maciej Szmigiero , David Hildenbrand , Quentin Perret , Michael Roth , Wang , Liam Merwick , Isaku Yamahata , "Kirill A . Shutemov" Content-Type: text/plain; charset="us-ascii" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 30, 2023, Sean Christopherson wrote: > On Mon, Oct 30, 2023, Paolo Bonzini wrote: > > On 10/27/23 20:21, Sean Christopherson wrote: > > > > > > + if (ioctl == KVM_SET_USER_MEMORY_REGION) > > > + size = sizeof(struct kvm_userspace_memory_region); > > > > This also needs a memset(&mem, 0, sizeof(mem)), otherwise the out-of-bounds > > access of the commit message becomes a kernel stack read. > > Ouch. There's some irony. Might be worth doing memset(&mem, -1, sizeof(mem)) > though as '0' is a valid file descriptor and a valid file offset. > > > Probably worth adding a check on valid flags here. > > Definitely needed. There's a very real bug here. But rather than duplicate flags > checking or plumb @ioctl all the way to __kvm_set_memory_region(), now that we > have the fancy guard(mutex) and there are no internal calls to kvm_set_memory_region(), > what if we: > > 1. Acquire/release slots_lock in __kvm_set_memory_region() Gah, this won't work with x86's usage, which acquire slots_lock quite far away from __kvm_set_memory_region() in several places. The rest of the idea still works, kvm_vm_ioctl_set_memory_region() will just need to take slots_lock manually. > 2. Call kvm_set_memory_region() from x86 code for the internal memslots > 3. Disallow *any* flags for internal memslots > 4. Open code check_memory_region_flags in kvm_vm_ioctl_set_memory_region() > 5. Pass @ioctl to kvm_vm_ioctl_set_memory_region() and allow KVM_MEM_PRIVATE > only for KVM_SET_USER_MEMORY_REGION2