diff options
| author | Marcelo Tosatti <mtosatti@redhat.com> | 2009-04-16 08:30:44 -0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@suse.de> | 2010-04-01 15:52:25 -0700 |
| commit | de2a051fb93911ce098404a46d46e5a1da652561 (patch) | |
| tree | 262094c148a596a22cd7e0565c1a683f9edfcbe4 | |
| parent | 1f059b24d2a9f0f15766d0f77acaaa3c8a163a3a (diff) | |
KVM: x86: check for cr3 validity in ioctl_set_sregs
commit 59839dfff5eabca01cc4e20b45797a60a80af8cb upstream.
Matt T. Yourst notes that kvm_arch_vcpu_ioctl_set_sregs lacks validity
checking for the new cr3 value:
"Userspace callers of KVM_SET_SREGS can pass a bogus value of cr3 to
the kernel. This will trigger a NULL pointer access in gfn_to_rmap()
when userspace next tries to call KVM_RUN on the affected VCPU and kvm
attempts to activate the new non-existent page table root.
This happens since kvm only validates that cr3 points to a valid guest
physical memory page when code *inside* the guest sets cr3. However, kvm
currently trusts the userspace caller (e.g. QEMU) on the host machine to
always supply a valid page table root, rather than properly validating
it along with the rest of the reloaded guest state."
http://sourceforge.net/tracker/?func=detail&atid=893831&aid=2687641&group_id=180599
Check for a valid cr3 address in kvm_arch_vcpu_ioctl_set_sregs, triple
fault in case of failure.
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
| -rw-r--r-- | arch/x86/kvm/x86.c | 8 |
1 files changed, 7 insertions, 1 deletions
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 99472249421..80ffc99d739 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3658,7 +3658,13 @@ int kvm_arch_vcpu_ioctl_set_sregs(struct kvm_vcpu *vcpu, vcpu->arch.cr2 = sregs->cr2; mmu_reset_needed |= vcpu->arch.cr3 != sregs->cr3; - vcpu->arch.cr3 = sregs->cr3; + + down_read(&vcpu->kvm->slots_lock); + if (gfn_to_memslot(vcpu->kvm, sregs->cr3 >> PAGE_SHIFT)) + vcpu->arch.cr3 = sregs->cr3; + else + set_bit(KVM_REQ_TRIPLE_FAULT, &vcpu->requests); + up_read(&vcpu->kvm->slots_lock); kvm_set_cr8(vcpu, sregs->cr8); |