On Friday 13 August 2010 15:19:11 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 <[email protected]>
> Cc: Thomas Gleixner <[email protected]>
> Cc: Ingo Molnar <[email protected]>
> Cc: "H. Peter Anvin" <[email protected]>
> Cc: Suresh Siddha <[email protected]>
> Cc: Brian Gerst <[email protected]>
> Cc: Avi Kivity <[email protected]>
> Cc: Robert Richter <[email protected]>
> Cc: Sheng Yang <[email protected]>
> Cc: Marcelo Tosatti <[email protected]>
> Cc: Gleb Natapov <[email protected]>
> Cc: Jan Kiszka <[email protected]>
Reviewed-by: Sheng Yang <[email protected]>
--
regards
Yang, Sheng
> ---
> 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;
--
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