On 12/01/2017 10:21 AM, Jim Mattson wrote:
From: Andrew Honig <ahonig@xxxxxxxxxx>
This fixes CVE-2017-1000407.
KVM allows guests to directly access I/O port 0x80 on Intel hosts. If
the guest floods this port with writes it generates exceptions and
instability in the host kernel, leading to a crash. With this change
guest writes to port 0x80 on Intel will behave the same as they
currently behave on AMD systems.
Prevent the flooding by removing the code that sets port 0x80 as a
passthrough port. This is essentially the same as upstream patch
99f85a28a78e96d28907fe036e1671a218fee597, except that patch was
for AMD chipsets and this patch is for Intel.
Signed-off-by: Andrew Honig <ahonig@xxxxxxxxxx>
Signed-off-by: Jim Mattson <jmattson@xxxxxxxxxx>
---
arch/x86/kvm/vmx.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
index d2b452d66363..d16abd1808eb 100644
--- a/arch/x86/kvm/vmx.c
+++ b/arch/x86/kvm/vmx.c
@@ -6753,12 +6753,7 @@ static __init int hardware_setup(void)
memset(vmx_vmread_bitmap, 0xff, PAGE_SIZE);
memset(vmx_vmwrite_bitmap, 0xff, PAGE_SIZE);
- /*
- * Allow direct access to the PC debug port (it is often used for I/O
- * delays, but the vmexits simply slow things down).
- */
memset(vmx_io_bitmap_a, 0xff, PAGE_SIZE);
- clear_bit(0x80, vmx_io_bitmap_a);
memset(vmx_io_bitmap_b, 0xff, PAGE_SIZE);
Reviewed-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx>
