4.2-stable review patch. If anyone has any objections, please let me know.
------------------
From: Marek Majtyka <marek.majtyka@xxxxxxxxx>
commit ca09f02f122b2ecb0f5ddfc5fd47b29ed657d4fd upstream.
A critical bug has been found in device memory stage1 translation for
VMs with more then 4GB of address space. Once vm_pgoff size is smaller
then pa (which is true for LPAE case, u32 and u64 respectively) some
more significant bits of pa may be lost as a shift operation is performed
on u32 and later cast onto u64.
Example: vm_pgoff(u32)=0x00210030, PAGE_SHIFT=12
expected pa(u64): 0x0000002010030000
produced pa(u64): 0x0000000010030000
The fix is to change the order of operations (casting first onto phys_addr_t
and then shifting).
Reviewed-by: Marc Zyngier <marc.zyngier@xxxxxxx>
[maz: fixed changelog and patch formatting]
Signed-off-by: Marek Majtyka <marek.majtyka@xxxxxxxxx>
Signed-off-by: Marc Zyngier <marc.zyngier@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/arm/kvm/mmu.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/arch/arm/kvm/mmu.c
+++ b/arch/arm/kvm/mmu.c
@@ -1792,8 +1792,10 @@ int kvm_arch_prepare_memory_region(struc
if (vma->vm_flags & VM_PFNMAP) {
gpa_t gpa = mem->guest_phys_addr +
(vm_start - mem->userspace_addr);
- phys_addr_t pa = (vma->vm_pgoff << PAGE_SHIFT) +
- vm_start - vma->vm_start;
+ phys_addr_t pa;
+
+ pa = (phys_addr_t)vma->vm_pgoff << PAGE_SHIFT;
+ pa += vm_start - vma->vm_start;
/* IO region dirty page logging not allowed */
if (memslot->flags & KVM_MEM_LOG_DIRTY_PAGES)
--
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