Re: [PATCH 0/2] Fix wild/dangling pointer in x86 ptp_kvm

[Paolo Bonzini <pbonzini@redhat.com>]

On 29/09/21 07:13, Zelin Deng wrote:
> When I was doing PTP_SYS_OFFSET_PRECISE ioctl in VM which has 128 vCPUs,
> I got error returned occasionally. Then I checked the routine of
> "getcrosststamp". I found in kvm_arch_ptp_get_crosststamp() of x86,
> pvclock vcpu time info was got from hv_clock arrary which has only 64
> elements. Hence this ioctl is executed on vCPU > 64, a wild/dangling
> pointer will be got, which had casued the error.
> To confirm this finding, I wrote a simple PTP_SYS_OFFSET_PRECISE ioctl
> test and used "taskset -c n" to run the test, when it was executed on
> vCPUs >= 64 it returned error.
> This patchset exposes this_cpu_pvti() to get per cpu pvclock vcpu time
> info of vCPUs >= 64 insdead of getting them from hv_clock arrary.
> 
> Zelin Deng (2):
>    x86/kvmclock: Move this_cpu_pvti into kvmclock.h
>    ptp: Fix ptp_kvm_getcrosststamp issue for x86 ptp_kvm
> 
>   arch/x86/include/asm/kvmclock.h | 14 ++++++++++++++
>   arch/x86/kernel/kvmclock.c      | 13 ++-----------
>   drivers/ptp/ptp_kvm_x86.c       |  9 ++-------
>   3 files changed, 18 insertions(+), 18 deletions(-)
> 

Queued, thanks.

Paolo