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Commit f45755b8 authored by Xiaotian Feng's avatar Xiaotian Feng Committed by Avi Kivity
Browse files

KVM: fix poison overwritten caused by using wrong xstate size 



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: default avatarXiaotian Feng <dfeng@redhat.com>
Reviewed-by: default avatarSheng Yang <sheng@linux.intel.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>
Signed-off-by: default avatarAvi Kivity <avi@redhat.com>
parent 3cfc2c42

arch/x86/kernel/i387.c

+1 −0
Original line number Diff line number Diff line
@@ -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;

arch/x86/kvm/x86.c

+2 −2
Original line number Diff line number Diff line
@@ -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;