lkml.org 
[lkml]   [2010]   [Aug]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH] kvm: fix poison overwritten caused by using wrong xstate size
    Avi, do you want to take this one or should I?

    -hpa

    On 08/13/2010 12:19 AM, Xiaotian Feng wrote:
    > fpu.state is allocated from task_xstate_cachep, the size of task_xstate_cachep
    > is xstate_size. xstate_size is set from cpuid instruction, which is often
    > smaller than sizeof(struct xsave_struct). kvm is using sizeof(struct xsave_struct)
    > to fill in/out fpu.state.xsave, as what we allocated for fpu.state is
    > xstate_size, kernel will write out of memory and caused poison/redzone/padding
    > overwritten warnings.
    >
    > Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
    > Cc: Thomas Gleixner <tglx@linutronix.de>
    > Cc: Ingo Molnar <mingo@redhat.com>
    > Cc: "H. Peter Anvin" <hpa@zytor.com>
    > Cc: Suresh Siddha <suresh.b.siddha@intel.com>
    > Cc: Brian Gerst <brgerst@gmail.com>
    > Cc: Avi Kivity <avi@redhat.com>
    > Cc: Robert Richter <robert.richter@amd.com>
    > Cc: Sheng Yang <sheng@linux.intel.com>
    > Cc: Marcelo Tosatti <mtosatti@redhat.com>
    > Cc: Gleb Natapov <gleb@redhat.com>
    > Cc: Jan Kiszka <jan.kiszka@siemens.com>
    > ---
    > arch/x86/kernel/i387.c | 1 +
    > arch/x86/kvm/x86.c | 4 ++--
    > 2 files changed, 3 insertions(+), 2 deletions(-)
    >
    > diff --git a/arch/x86/kernel/i387.c b/arch/x86/kernel/i387.c
    > index 1f11f5c..a46cb35 100644
    > --- a/arch/x86/kernel/i387.c
    > +++ b/arch/x86/kernel/i387.c
    > @@ -40,6 +40,7 @@
    >
    > static unsigned int mxcsr_feature_mask __read_mostly = 0xffffffffu;
    > unsigned int xstate_size;
    > +EXPORT_SYMBOL_GPL(xstate_size);
    > unsigned int sig_xstate_ia32_size = sizeof(struct _fpstate_ia32);
    > static struct i387_fxsave_struct fx_scratch __cpuinitdata;
    >
    > diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
    > index 25f1907..3a09c62 100644
    > --- a/arch/x86/kvm/x86.c
    > +++ b/arch/x86/kvm/x86.c
    > @@ -2387,7 +2387,7 @@ static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
    > if (cpu_has_xsave)
    > memcpy(guest_xsave->region,
    > &vcpu->arch.guest_fpu.state->xsave,
    > - sizeof(struct xsave_struct));
    > + xstate_size);
    > else {
    > memcpy(guest_xsave->region,
    > &vcpu->arch.guest_fpu.state->fxsave,
    > @@ -2405,7 +2405,7 @@ static int kvm_vcpu_ioctl_x86_set_xsave(struct kvm_vcpu *vcpu,
    >
    > if (cpu_has_xsave)
    > memcpy(&vcpu->arch.guest_fpu.state->xsave,
    > - guest_xsave->region, sizeof(struct xsave_struct));
    > + guest_xsave->region, xstate_size);
    > else {
    > if (xstate_bv & ~XSTATE_FPSSE)
    > return -EINVAL;



    \
     
     \ /
      Last update: 2010-08-13 23:07    [W:0.025 / U:33.072 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site