From f45755b8346f1a089ca7957dce5f4c3c6cb26e6f Mon Sep 17 00:00:00 2001 From: Xiaotian Feng Date: Fri, 13 Aug 2010 15:19:11 +0800 Subject: [PATCH] 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: Xiaotian Feng Reviewed-by: Sheng Yang Cc: Thomas Gleixner Cc: Ingo Molnar Cc: "H. Peter Anvin" Cc: Suresh Siddha Cc: Brian Gerst Cc: Avi Kivity Cc: Robert Richter Cc: Sheng Yang Cc: Marcelo Tosatti Cc: Gleb Natapov Cc: Jan Kiszka Signed-off-by: Avi Kivity --- 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 c4444bc..f855658 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 97aab03..bb2347a 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; -- 2.7.4