From: Quentin Casasnovas Date: Fri, 17 Oct 2014 20:55:59 +0000 (+0200) Subject: kvm: fix excessive pages un-pinning in kvm_iommu_map error path. X-Git-Tag: v3.2.65~85 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=8200024f8aa83d5900480c74f65f46d536a4fe62 kvm: fix excessive pages un-pinning in kvm_iommu_map error path. commit 3d32e4dbe71374a6780eaf51d719d76f9a9bf22f upstream. The third parameter of kvm_unpin_pages() when called from kvm_iommu_map_pages() is wrong, it should be the number of pages to un-pin and not the page size. This error was facilitated with an inconsistent API: kvm_pin_pages() takes a size, but kvn_unpin_pages() takes a number of pages, so fix the problem by matching the two. This was introduced by commit 350b8bd ("kvm: iommu: fix the third parameter of kvm_iommu_put_pages (CVE-2014-3601)"), which fixes the lack of un-pinning for pages intended to be un-pinned (i.e. memory leak) but unfortunately potentially aggravated the number of pages we un-pin that should have stayed pinned. As far as I understand though, the same practical mitigations apply. This issue was found during review of Red Hat 6.6 patches to prepare Ksplice rebootless updates. Thanks to Vegard for his time on a late Friday evening to help me in understanding this code. Fixes: 350b8bd ("kvm: iommu: fix the third parameter of... (CVE-2014-3601)") Cc: stable@vger.kernel.org Signed-off-by: Quentin Casasnovas Signed-off-by: Vegard Nossum Signed-off-by: Jamie Iles Reviewed-by: Sasha Levin Signed-off-by: Paolo Bonzini [bwh: Backported to 3.2: kvm_pin_pages() also takes a struct kvm *kvm param] Signed-off-by: Ben Hutchings --- diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c index c946700927fa..e32c93ca6446 100644 --- a/virt/kvm/iommu.c +++ b/virt/kvm/iommu.c @@ -43,13 +43,13 @@ static void kvm_iommu_put_pages(struct kvm *kvm, gfn_t base_gfn, unsigned long npages); static pfn_t kvm_pin_pages(struct kvm *kvm, struct kvm_memory_slot *slot, - gfn_t gfn, unsigned long size) + gfn_t gfn, unsigned long npages) { gfn_t end_gfn; pfn_t pfn; pfn = gfn_to_pfn_memslot(kvm, slot, gfn); - end_gfn = gfn + (size >> PAGE_SHIFT); + end_gfn = gfn + npages; gfn += 1; if (is_error_pfn(pfn)) @@ -117,7 +117,7 @@ int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot) * Pin all pages we are about to map in memory. This is * important because we unmap and unpin in 4kb steps later. */ - pfn = kvm_pin_pages(kvm, slot, gfn, page_size); + pfn = kvm_pin_pages(kvm, slot, gfn, page_size >> PAGE_SHIFT); if (is_error_pfn(pfn)) { gfn += 1; continue; @@ -129,7 +129,7 @@ int kvm_iommu_map_pages(struct kvm *kvm, struct kvm_memory_slot *slot) if (r) { printk(KERN_ERR "kvm_iommu_map_address:" "iommu failed to map pfn=%llx\n", pfn); - kvm_unpin_pages(kvm, pfn, page_size); + kvm_unpin_pages(kvm, pfn, page_size >> PAGE_SHIFT); goto unmap_pages; }