This is a note to let you know that I've just added the patch titled
kvm: fix excessive pages un-pinning in kvm_iommu_map error path.
to the 3.10-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
kvm-fix-excessive-pages-un-pinning-in-kvm_iommu_map-error-path.patch
and it can be found in the queue-3.10 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 3d32e4dbe71374a6780eaf51d719d76f9a9bf22f Mon Sep 17 00:00:00 2001
From: Quentin Casasnovas <[email protected]>
Date: Fri, 17 Oct 2014 22:55:59 +0200
Subject: kvm: fix excessive pages un-pinning in kvm_iommu_map error path.
From: Quentin Casasnovas <[email protected]>
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 <[email protected]>
Signed-off-by: Vegard Nossum <[email protected]>
Signed-off-by: Jamie Iles <[email protected]>
Reviewed-by: Sasha Levin <[email protected]>
Signed-off-by: Paolo Bonzini <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
virt/kvm/iommu.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
--- a/virt/kvm/iommu.c
+++ b/virt/kvm/iommu.c
@@ -43,13 +43,13 @@ static void kvm_iommu_put_pages(struct k
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,
* 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,
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;
}
Patches currently in stable-queue which might be from
[email protected] are
queue-3.10/kvm-fix-excessive-pages-un-pinning-in-kvm_iommu_map-error-path.patch
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