lkml.org 
[lkml]   [2011]   [Jan]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[34-longterm 235/260] KVM: VMX: Fix host GDT.LIMIT corruption
    Date
    From: Avi Kivity <avi@redhat.com>

    commit 3444d7da1839b851eefedd372978d8a982316c36 upstream.

    vmx does not restore GDT.LIMIT to the host value, instead it sets it to 64KB.
    This means host userspace can learn a few bits of host memory.

    Fix by reloading GDTR when we load other host state.

    Signed-off-by: Avi Kivity <avi@redhat.com>
    Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
    Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
    ---
    arch/x86/kvm/vmx.c | 4 ++++
    1 files changed, 4 insertions(+), 0 deletions(-)

    diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
    index 3c86c42..11db911 100644
    --- a/arch/x86/kvm/vmx.c
    +++ b/arch/x86/kvm/vmx.c
    @@ -170,6 +170,7 @@ static u64 construct_eptp(unsigned long root_hpa);
    static DEFINE_PER_CPU(struct vmcs *, vmxarea);
    static DEFINE_PER_CPU(struct vmcs *, current_vmcs);
    static DEFINE_PER_CPU(struct list_head, vcpus_on_cpu);
    +static DEFINE_PER_CPU(struct desc_ptr, host_gdt);

    static unsigned long *vmx_io_bitmap_a;
    static unsigned long *vmx_io_bitmap_b;
    @@ -717,6 +718,7 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx)
    wrmsrl(MSR_KERNEL_GS_BASE, vmx->msr_host_kernel_gs_base);
    }
    #endif
    + load_gdt(&__get_cpu_var(host_gdt));
    }

    static void vmx_load_host_state(struct vcpu_vmx *vmx)
    @@ -1218,6 +1220,8 @@ static int hardware_enable(void *garbage)

    ept_sync_global();

    + store_gdt(&__get_cpu_var(host_gdt));
    +
    return 0;
    }

    --
    1.7.3.3


    \
     
     \ /
      Last update: 2011-01-02 08:37    [W:4.087 / U:0.144 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site