From 350b8bdd689cd2ab2c67c8a86a0be86cfa0751a7 Mon Sep 17 00:00:00 2001 From: "Michael S. Tsirkin" Date: Tue, 19 Aug 2014 19:14:50 +0800 Subject: [PATCH] kvm: iommu: fix the third parameter of kvm_iommu_put_pages (CVE-2014-3601) 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 Cc: stable@vger.kernel.org Signed-off-by: Michael S. Tsirkin Signed-off-by: Paolo Bonzini --- Reading git-format-patch failed