From: Avi Kivity Date: Sun, 22 Apr 2007 09:28:49 +0000 (+0300) Subject: KVM: MMU: Fix host memory corruption on i386 with >= 4GB ram X-Git-Tag: v2.6.20.11~29 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=036bb8535c517d6ea5669337ed709cd975369a2b;p=thirdparty%2Fkernel%2Fstable.git 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 Signed-off-by: Avi Kivity Signed-off-by: Greg Kroah-Hartman --- diff --git a/drivers/kvm/mmu.c b/drivers/kvm/mmu.c index 1e09d4e3b0536..1b5e1895c782c 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);