This is a note to let you know that I've just added the patch titled

KVM: VMX: remove I/O port 0x80 bypass on Intel hosts

to the 3.18-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: kvm-vmx-remove-i-o-port-0x80-bypass-on-intel-hosts.patch and it can be found in the queue-3.18 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From d59d51f088014f25c2562de59b9abff4f42a7468 Mon Sep 17 00:00:00 2001

From: Andrew Honig ahonig@google.com Date: Fri, 1 Dec 2017 10:21:09 -0800 Subject: KVM: VMX: remove I/O port 0x80 bypass on Intel hosts MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit

From: Andrew Honig ahonig@google.com

commit d59d51f088014f25c2562de59b9abff4f42a7468 upstream.

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@google.com Signed-off-by: Jim Mattson jmattson@google.com Fixes: fdef3ad1b386 ("KVM: VMX: Enable io bitmaps to avoid IO port 0x80 VMEXITs") Signed-off-by: Radim Krčmář rkrcmar@redhat.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

--- arch/x86/kvm/vmx.c | 5 ----- 1 file changed, 5 deletions(-)

--- a/arch/x86/kvm/vmx.c +++ b/arch/x86/kvm/vmx.c @@ -9280,12 +9280,7 @@ static int __init vmx_init(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);

Patches currently in stable-queue which might be from ahonig@google.com are

queue-3.18/kvm-vmx-remove-i-o-port-0x80-bypass-on-intel-hosts.patch