From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935320AbaICXmH (ORCPT ); Wed, 3 Sep 2014 19:42:07 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:45237 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933212AbaICWF6 (ORCPT ); Wed, 3 Sep 2014 18:05:58 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Jack Morgenstein , "Michael S. Tsirkin" , Paolo Bonzini Subject: [PATCH 3.10 32/55] kvm: iommu: fix the third parameter of kvm_iommu_put_pages (CVE-2014-3601) Date: Wed, 3 Sep 2014 15:05:22 -0700 Message-Id: <20140903220459.090482687@linuxfoundation.org> X-Mailer: git-send-email 2.1.0 In-Reply-To: <20140903220453.653576908@linuxfoundation.org> References: <20140903220453.653576908@linuxfoundation.org> User-Agent: quilt/0.63-1 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 3.10-stable review patch. If anyone has any objections, please let me know. ------------------ From: "Michael S. Tsirkin" commit 350b8bdd689cd2ab2c67c8a86a0be86cfa0751a7 upstream. The third parameter of kvm_iommu_put_pages is wrong, It should be 'gfn - slot->base_gfn'. By making gfn very large, malicious guest or userspace can cause kvm to go to this error path, and subsequently to pass a huge value as size. Alternatively if gfn is small, then pages would be pinned but never unpinned, causing host memory leak and local DOS. Passing a reasonable but large value could be the most dangerous case, because it would unpin a page that should have stayed pinned, and thus allow the device to DMA into arbitrary memory. However, this cannot happen because of the condition that can trigger the error: - out of memory (where you can't allocate even a single page) should not be possible for the attacker to trigger - when exceeding the iommu's address space, guest pages after gfn will also exceed the iommu's address space, and inside kvm_iommu_put_pages() the iommu_iova_to_phys() will fail. The page thus would not be unpinned at all. Reported-by: Jack Morgenstein Signed-off-by: Michael S. Tsirkin Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- virt/kvm/iommu.c | 19 ++++++++++--------- 1 file changed, 10 insertions(+), 9 deletions(-) --- a/virt/kvm/iommu.c +++ b/virt/kvm/iommu.c @@ -61,6 +61,14 @@ static pfn_t kvm_pin_pages(struct kvm_me return pfn; } +static void kvm_unpin_pages(struct kvm *kvm, pfn_t pfn, unsigned long npages) +{ + unsigned long i; + + for (i = 0; i < npages; ++i) + kvm_release_pfn_clean(pfn + i); +} + int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot) { gfn_t gfn, end_gfn; @@ -123,6 +131,7 @@ int kvm_iommu_map_pages(struct kvm *kvm, if (r) { printk(KERN_ERR "kvm_iommu_map_address:" "iommu failed to map pfn=%llx\n", pfn); + kvm_unpin_pages(kvm, pfn, page_size); goto unmap_pages; } @@ -134,7 +143,7 @@ int kvm_iommu_map_pages(struct kvm *kvm, return 0; unmap_pages: - kvm_iommu_put_pages(kvm, slot->base_gfn, gfn); + kvm_iommu_put_pages(kvm, slot->base_gfn, gfn - slot->base_gfn); return r; } @@ -272,14 +281,6 @@ out_unlock: return r; } -static void kvm_unpin_pages(struct kvm *kvm, pfn_t pfn, unsigned long npages) -{ - unsigned long i; - - for (i = 0; i < npages; ++i) - kvm_release_pfn_clean(pfn + i); -} - static void kvm_iommu_put_pages(struct kvm *kvm, gfn_t base_gfn, unsigned long npages) {