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authorQuentin Casasnovas <quentin.casasnovas@oracle.com>2014-10-17 22:55:59 +0200
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2014-11-14 08:47:56 -0800
commit3ea61129fec62fbb7fba38e60d00e4f9d776cfa5 (patch)
tree73a0c4af929edbae9bbe6f2f54276862ca0776db /virt
parent6033d64297fac0c26284fe9b7ca8751906dcf277 (diff)
downloadlinux-linaro-stable-3ea61129fec62fbb7fba38e60d00e4f9d776cfa5.tar.gz
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)") Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com> Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com> Signed-off-by: Jamie Iles <jamie.iles@oracle.com> Reviewed-by: Sasha Levin <sasha.levin@oracle.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'virt')
-rw-r--r--virt/kvm/iommu.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index dec997188dfb..a650aa48c786 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_memory_slot *slot, gfn_t gfn,
- unsigned long size)
+ unsigned long npages)
{
gfn_t end_gfn;
pfn_t pfn;
pfn = gfn_to_pfn_memslot(slot, gfn);
- end_gfn = gfn + (size >> PAGE_SHIFT);
+ end_gfn = gfn + npages;
gfn += 1;
if (is_error_noslot_pfn(pfn))
@@ -119,7 +119,7 @@ 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(slot, gfn, page_size);
+ pfn = kvm_pin_pages(slot, gfn, page_size >> PAGE_SHIFT);
if (is_error_noslot_pfn(pfn)) {
gfn += 1;
continue;
@@ -131,7 +131,7 @@ 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;
}