On 2017/12/05 01:10, Jim Mattson wrote:
Google has carried this patch since long before my time. I would
suggest modifying the kvm-unit-test to (a) unroll the loop ~1000
times, and (b) execute out to port 0x80 from ~64 vcpu threads in
parallel.
Jim, could you reproduce it on all of your machine types?
I can't reproduce it on 2 types of my machine.. btw, it is not a good
idle to
open reproduction here:(..
I do believe you can reproduce on you machine. could you have a try:
without guest, flood 80 port with writes in host kernel.. does it lead
to a crash?
if host kernel crash, does it a machine hardware issue, kernel issue, or
both?
Quan
Alibaba Cloud
On Mon, Dec 4, 2017 at 4:44 AM, Wanpeng Li <kernellwp@xxxxxxxxx> wrote:
Hi Jim,
2017-12-02 2:21 GMT+08:00 Jim Mattson <jmattson@xxxxxxxxxx>:
From: Andrew Honig <ahonig@xxxxxxxxxx>
This fixes CVE-2017-1000407.
Do you observe a real issue on recent Intel boxes? In addition, how to
reproduce? Actually there is a testcase in kvm-unit-tests which can
run 10 million times ioport 0x80 write and I didn't observe any issue
before. :)
Regards,
Wanpeng Li
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);
--
2.15.0.531.g2ccb3012c9-goog
