From: Quentin Casasnovas <quentin.casasnovas@xxxxxxxxxx>
3.4.106-rc1 review patch. If anyone has any objections, please let me know.
------------------
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@xxxxxxxxxx>
Signed-off-by: Vegard Nossum <vegard.nossum@xxxxxxxxxx>
Signed-off-by: Jamie Iles <jamie.iles@xxxxxxxxxx>
Reviewed-by: Sasha Levin <sasha.levin@xxxxxxxxxx>
Signed-off-by: Paolo Bonzini <pbonzini@xxxxxxxxxx>
[lizf: Backported to 3.4: adjust context]
Signed-off-by: Zefan Li <lizefan@xxxxxxxxxx>
---
virt/kvm/iommu.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/virt/kvm/iommu.c b/virt/kvm/iommu.c
index defc9ba..3225903 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;
}
--
1.9.1
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