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authorAvi Kivity <avi@qumranet.com>2007-04-22 12:28:49 +0300
committerGreg Kroah-Hartman <gregkh@suse.de>2007-05-01 17:05:54 -0700
commit036bb8535c517d6ea5669337ed709cd975369a2b (patch)
treee9ba3427ae9415abc873cae4c5fb5db1b8e1feb0
parent1c4b6343a17186145fdf658939c5682e916905bc (diff)
KVM: MMU: Fix host memory corruption on i386 with >= 4GB ram
PAGE_MASK is an unsigned long, so using it to mask physical addresses on i386 (which are 64-bit wide) leads to truncation. This can result in page->private of unrelated memory pages being modified, with disasterous results. Fix by not using PAGE_MASK for physical addresses; instead calculate the correct value directly from PAGE_SIZE. Also fix a similar BUG_ON(). Acked-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Avi Kivity <avi@qumranet.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
-rw-r--r--drivers/kvm/mmu.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c
index 1e09d4e3b053..1b5e1895c782 100644
--- a/drivers/kvm/mmu.c
+++ b/drivers/kvm/mmu.c
@@ -131,7 +131,7 @@ static int dbg = 1;
(((address) >> PT32_LEVEL_SHIFT(level)) & ((1 << PT32_LEVEL_BITS) - 1))
-#define PT64_BASE_ADDR_MASK (((1ULL << 52) - 1) & PAGE_MASK)
+#define PT64_BASE_ADDR_MASK (((1ULL << 52) - 1) & ~(u64)(PAGE_SIZE-1))
#define PT64_DIR_BASE_ADDR_MASK \
(PT64_BASE_ADDR_MASK & ~((1ULL << (PAGE_SHIFT + PT64_LEVEL_BITS)) - 1))
@@ -406,8 +406,8 @@ static void rmap_write_protect(struct kvm_vcpu *vcpu, u64 gfn)
spte = desc->shadow_ptes[0];
}
BUG_ON(!spte);
- BUG_ON((*spte & PT64_BASE_ADDR_MASK) !=
- page_to_pfn(page) << PAGE_SHIFT);
+ BUG_ON((*spte & PT64_BASE_ADDR_MASK) >> PAGE_SHIFT
+ != page_to_pfn(page));
BUG_ON(!(*spte & PT_PRESENT_MASK));
BUG_ON(!(*spte & PT_WRITABLE_MASK));
rmap_printk("rmap_write_protect: spte %p %llx\n", spte, *spte);