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KVM: Fix a race condition for usage of is_hwpoison_address() 

is_hwpoison_address accesses the page table, so the caller must hold
current->mm->mmap_sem in read mode. So fix its usage in hva_to_pfn of
kvm accordingly.

Comment is_hwpoison_address to remind other users.

Reported-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Huang Ying <ying.huang@intel.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
This commit is contained in:
Huang Ying 2010-06-22 14:23:11 +08:00 committed by Avi Kivity
parent 6c3f604117
commit bbeb34062f
2 changed files with 5 additions and 1 deletions
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3
mm/memory-failure.c
View File

@ -1298,6 +1298,9 @@ int soft_offline_page(struct page *page, int flags)
return ret; return ret;
} }
/*
* The caller must hold current->mm->mmap_sem in read mode.
*/
int is_hwpoison_address(unsigned long addr) int is_hwpoison_address(unsigned long addr)
{ {
pgd_t *pgdp; pgd_t *pgdp;

3
virt/kvm/kvm_main.c
View File

@ -947,12 +947,13 @@ static pfn_t hva_to_pfn(struct kvm *kvm, unsigned long addr)
if (unlikely(npages != 1)) { if (unlikely(npages != 1)) {
struct vm_area_struct *vma; struct vm_area_struct *vma;
down_read(&current->mm->mmap_sem);
if (is_hwpoison_address(addr)) { if (is_hwpoison_address(addr)) {
up_read(&current->mm->mmap_sem);
get_page(hwpoison_page); get_page(hwpoison_page);
return page_to_pfn(hwpoison_page); return page_to_pfn(hwpoison_page);
} }
down_read(&current->mm->mmap_sem);
vma = find_vma(current->mm, addr); vma = find_vma(current->mm, addr);
if (vma == NULL || addr < vma->vm_start || if (vma == NULL || addr < vma->vm_start ||