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| author | Marcelo Tosatti <mtosatti@redhat.com> | 2009-04-16 13:30:44 +0200 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-06-10 10:48:43 +0200 |
| commit | 59839dfff5eabca01cc4e20b45797a60a80af8cb (patch) | |
| tree | e6818499bdfa84dea4634354288ed50c677aaec8 /arch | |
| parent | KVM: ia64: Don't hold slots_lock in guest mode (diff) | |
| download | linux-59839dfff5eabca01cc4e20b45797a60a80af8cb.tar.xz linux-59839dfff5eabca01cc4e20b45797a60a80af8cb.zip | |
KVM: x86: check for cr3 validity in ioctl_set_sregs
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.
Cc: stable@kernel.org
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'arch')
| -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 ffbb2c818d78..2bad49b535c8 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3993,7 +3993,13 @@ 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); |