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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 136D5C433EF for ; Tue, 5 Oct 2021 15:41:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E837F60F23 for ; Tue, 5 Oct 2021 15:41:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236139AbhJEPni (ORCPT ); Tue, 5 Oct 2021 11:43:38 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34518 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235992AbhJEPnh (ORCPT ); Tue, 5 Oct 2021 11:43:37 -0400 Received: from mail-pj1-x102e.google.com (mail-pj1-x102e.google.com [IPv6:2607:f8b0:4864:20::102e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C33D7C061753 for ; Tue, 5 Oct 2021 08:41:46 -0700 (PDT) Received: by mail-pj1-x102e.google.com with SMTP id d13-20020a17090ad3cd00b0019e746f7bd4so2354775pjw.0 for ; Tue, 05 Oct 2021 08:41:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=5/7o5EIsmXSiuzP1m4Q+SWodBgxhNUVp7n/GckW+Jrk=; b=Dl8yKD10zzy661mtoaa0QdpladaehtORzyWw8GaN0/Az/CLUUH9TBPrvwKoF6GQQs4 PXQvWfPWsBHlEOT1LDRGkdd+aZjK6DRTpa1NLkqjig72gEJcG4FndrVbdUbpkylaDuVE dEvFRUSrC8x5KMWvIGfiEXlMjgyxZsdZ5ptfDNNxIkGk7mqOpn7RsNMdoV6zpFvZHwLr 43JDIpGK7Oj35lRWTSwrW1t08d42apKif4VNtj6l94zOjuK69osIqs4rmWNN6YuvH4wU Koo4kZjiSqGO4GZ8Ej9MJ8loW3X6iqAp8C6bae/u4eu4uAWONJp01OYo7yF0ISHNPGY1 noEQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=5/7o5EIsmXSiuzP1m4Q+SWodBgxhNUVp7n/GckW+Jrk=; b=cXjdlXodCGMNyGTrmi00PYQbD4qHLlvNQPxuVh3jd+i5Pt49jpmAWo2sj5B91mFM0/ bmpWnDzaBhfXBSiVfXaPTGnNL8ieAz8+l3BMyt2e/9Na6qNerHi803BNgYZvKWsL1DTP aStlDGEpAJOg8wHAplGOqPXsuCzgJuxjI4x7GppMApo/6PSOSgOS2vPg48gx3C2vbyq1 UlL5C0lNhgfbWi/APcacBcLBoV4+XpzRJ/Xi32xY2Le4CT0vMKrzRtNr3uUEu0Jw7Fr+ aoTzQ2FQkHriVTxJeE+n/SXHzH1OHFskZWmH7I+44Rz6NXxtxaVl2BwSiE+OPdG6h70n 2eCw== X-Gm-Message-State: AOAM531/VWwo5vutC72QDsufVZEjW6xQug2ofCogfBO9aMbHpygYokJp TaROtzYWOAEUYabbxhIwwPkYvw== X-Google-Smtp-Source: ABdhPJz7Eu5WhkXk+3OVsJv0v8fEKxdtoYqJuoAyIMqCgFUECW/V7fiWss45GtxUT3gd2sgeCsfWCg== X-Received: by 2002:a17:90a:890a:: with SMTP id u10mr4555711pjn.40.1633448506134; Tue, 05 Oct 2021 08:41:46 -0700 (PDT) Received: from google.com (157.214.185.35.bc.googleusercontent.com. [35.185.214.157]) by smtp.gmail.com with ESMTPSA id t1sm17244661pgf.78.2021.10.05.08.41.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 Oct 2021 08:41:45 -0700 (PDT) Date: Tue, 5 Oct 2021 15:41:42 +0000 From: Sean Christopherson To: Colin King Cc: Paolo Bonzini , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , Thomas Gleixner , Ingo Molnar , Borislav Petkov , x86@kernel.org, "H . Peter Anvin" , David Stevens , kvm@vger.kernel.org, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH][next] KVM: x86: Fix allocation sizeof argument Message-ID: References: <20211001110106.15056-1-colin.king@canonical.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211001110106.15056-1-colin.king@canonical.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 01, 2021, Colin King wrote: > From: Colin Ian King > > The allocation for *gfn_track should be for a slot->npages lot of > short integers, however the current allocation is using sizeof(*gfn_track) > and that is the size of a pointer, which is too large. Fix this by > using sizeof(**gfn_track) instead. > > Addresses-Coverity: ("Wrong sizeof argument") > Fixes: 35b330bba6a7 ("KVM: x86: only allocate gfn_track when necessary") > Signed-off-by: Colin Ian King > --- > arch/x86/kvm/mmu/page_track.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c > index bb5d60bd4dbf..5b785a5f7dc9 100644 > --- a/arch/x86/kvm/mmu/page_track.c > +++ b/arch/x86/kvm/mmu/page_track.c > @@ -92,7 +92,7 @@ int kvm_page_track_enable_mmu_write_tracking(struct kvm *kvm) > slots = __kvm_memslots(kvm, i); > kvm_for_each_memslot(slot, slots) { > gfn_track = slot->arch.gfn_track + KVM_PAGE_TRACK_WRITE; > - *gfn_track = kvcalloc(slot->npages, sizeof(*gfn_track), > + *gfn_track = kvcalloc(slot->npages, sizeof(**gfn_track), > GFP_KERNEL_ACCOUNT); Eww (not your patch, the original code). IMO the double indirection is completely unnecessary, e.g. I find this far easier to follow diff --git a/arch/x86/kvm/mmu/page_track.c b/arch/x86/kvm/mmu/page_track.c index bb5d60bd4dbf..8cae41b831dd 100644 --- a/arch/x86/kvm/mmu/page_track.c +++ b/arch/x86/kvm/mmu/page_track.c @@ -75,7 +75,7 @@ int kvm_page_track_enable_mmu_write_tracking(struct kvm *kvm) { struct kvm_memslots *slots; struct kvm_memory_slot *slot; - unsigned short **gfn_track; + unsigned short *gfn_track; int i; if (write_tracking_enabled(kvm)) @@ -91,13 +91,13 @@ int kvm_page_track_enable_mmu_write_tracking(struct kvm *kvm) for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { slots = __kvm_memslots(kvm, i); kvm_for_each_memslot(slot, slots) { - gfn_track = slot->arch.gfn_track + KVM_PAGE_TRACK_WRITE; - *gfn_track = kvcalloc(slot->npages, sizeof(*gfn_track), - GFP_KERNEL_ACCOUNT); - if (*gfn_track == NULL) { + gfn_track = kvcalloc(slot->npages, sizeof(*gfn_track), + GFP_KERNEL_ACCOUNT); + if (gfn_track == NULL) { mutex_unlock(&kvm->slots_arch_lock); return -ENOMEM; } + slot->arch.gfn_track[KVM_PAGE_TRACK_WRITE] = gfn_track; } } > if (*gfn_track == NULL) { > mutex_unlock(&kvm->slots_arch_lock); Hrm, this fails to free the gfn_track allocations for previous memslots. The on-demand rmaps code has the exact same bug (it frees rmaps for previous lpages in the _current_ slot, but does not free previous slots). And having two separate flows (and flags) for rmaps vs. gfn_track is pointless, and means we have to maintain two near-identical copies of non-obvious code. Paolo, is it too late to just drop the original deae4a10f166 ("KVM: x86: only allocate gfn_track when necessary")? > -- > 2.32.0 >