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=-16.5 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=unavailable 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 B5726C432BE for ; Mon, 23 Aug 2021 14:30:56 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 87AB3600CD for ; Mon, 23 Aug 2021 14:30:56 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230153AbhHWObi (ORCPT ); Mon, 23 Aug 2021 10:31:38 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:57466 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230212AbhHWObf (ORCPT ); Mon, 23 Aug 2021 10:31:35 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629729052; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=gAk+4KSA7ARdoYI0TMZIFG727Vb77x9IC9rj5AiT9Dc=; b=W6bD25Ygc5UyK38mWfJ2orFblNj21NendQSpPfnEQcSnR8RHb+4pVD/O0y5LP3w9E7wqrq Ck8YLY/uOn3IFf7s5HTOkyIl1g5p2LCG0oVIPN8x3fN+2sgtEt6tE/mITi6EvhbDTjeTja nd5RnuLtHpBUO0wusqmVQBlRQprhrxU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-47-o4UY9sSgMpG0XHeU6jl7BQ-1; Mon, 23 Aug 2021 10:30:51 -0400 X-MC-Unique: o4UY9sSgMpG0XHeU6jl7BQ-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id B1E021082922; Mon, 23 Aug 2021 14:30:46 +0000 (UTC) Received: from vitty.brq.redhat.com (unknown [10.40.195.132]) by smtp.corp.redhat.com (Postfix) with ESMTP id AC7352719D; Mon, 23 Aug 2021 14:30:44 +0000 (UTC) From: Vitaly Kuznetsov To: kvm@vger.kernel.org, Paolo Bonzini Cc: Sean Christopherson , Wanpeng Li , Jim Mattson , "Dr. David Alan Gilbert" , Nitesh Narayan Lal , linux-kernel@vger.kernel.org Subject: [PATCH v2 4/4] KVM: x86: Fix stack-out-of-bounds memory access from ioapic_write_indirect() Date: Mon, 23 Aug 2021 16:30:28 +0200 Message-Id: <20210823143028.649818-5-vkuznets@redhat.com> In-Reply-To: <20210823143028.649818-1-vkuznets@redhat.com> References: <20210823143028.649818-1-vkuznets@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KASAN reports the following issue: BUG: KASAN: stack-out-of-bounds in kvm_make_vcpus_request_mask+0x174/0x440 [kvm] Read of size 8 at addr ffffc9001364f638 by task qemu-kvm/4798 CPU: 0 PID: 4798 Comm: qemu-kvm Tainted: G X --------- --- Hardware name: AMD Corporation DAYTONA_X/DAYTONA_X, BIOS RYM0081C 07/13/2020 Call Trace: dump_stack+0xa5/0xe6 print_address_description.constprop.0+0x18/0x130 ? kvm_make_vcpus_request_mask+0x174/0x440 [kvm] __kasan_report.cold+0x7f/0x114 ? kvm_make_vcpus_request_mask+0x174/0x440 [kvm] kasan_report+0x38/0x50 kasan_check_range+0xf5/0x1d0 kvm_make_vcpus_request_mask+0x174/0x440 [kvm] kvm_make_scan_ioapic_request_mask+0x84/0xc0 [kvm] ? kvm_arch_exit+0x110/0x110 [kvm] ? sched_clock+0x5/0x10 ioapic_write_indirect+0x59f/0x9e0 [kvm] ? static_obj+0xc0/0xc0 ? __lock_acquired+0x1d2/0x8c0 ? kvm_ioapic_eoi_inject_work+0x120/0x120 [kvm] The problem appears to be that 'vcpu_bitmap' is allocated as a single long on stack and it should really be KVM_MAX_VCPUS long. We also seem to clear the lower 16 bits of it with bitmap_zero() for no particular reason (my guess would be that 'bitmap' and 'vcpu_bitmap' variables in kvm_bitmap_or_dest_vcpus() caused the confusion: while the later is indeed 16-bit long, the later should accommodate all possible vCPUs). Fixes: 7ee30bc132c6 ("KVM: x86: deliver KVM IOAPIC scan request to target vCPUs") Fixes: 9a2ae9f6b6bb ("KVM: x86: Zero the IOAPIC scan request dest vCPUs bitmap") Reported-by: Dr. David Alan Gilbert Signed-off-by: Vitaly Kuznetsov --- arch/x86/kvm/ioapic.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c index ff005fe738a4..92cd4b02e9ba 100644 --- a/arch/x86/kvm/ioapic.c +++ b/arch/x86/kvm/ioapic.c @@ -319,7 +319,7 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val) unsigned index; bool mask_before, mask_after; union kvm_ioapic_redirect_entry *e; - unsigned long vcpu_bitmap; + unsigned long vcpu_bitmap[BITS_TO_LONGS(KVM_MAX_VCPUS)]; int old_remote_irr, old_delivery_status, old_dest_id, old_dest_mode; switch (ioapic->ioregsel) { @@ -384,9 +384,9 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val) irq.shorthand = APIC_DEST_NOSHORT; irq.dest_id = e->fields.dest_id; irq.msi_redir_hint = false; - bitmap_zero(&vcpu_bitmap, 16); + bitmap_zero(vcpu_bitmap, KVM_MAX_VCPUS); kvm_bitmap_or_dest_vcpus(ioapic->kvm, &irq, - &vcpu_bitmap); + vcpu_bitmap); if (old_dest_mode != e->fields.dest_mode || old_dest_id != e->fields.dest_id) { /* @@ -399,10 +399,10 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val) kvm_lapic_irq_dest_mode( !!e->fields.dest_mode); kvm_bitmap_or_dest_vcpus(ioapic->kvm, &irq, - &vcpu_bitmap); + vcpu_bitmap); } kvm_make_scan_ioapic_request_mask(ioapic->kvm, - &vcpu_bitmap); + vcpu_bitmap); } else { kvm_make_scan_ioapic_request(ioapic->kvm); } -- 2.31.1