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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 <dfeng@redhat.com>
Reviewed-by: Sheng 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: Avi Kivity <avi@redhat.com>
This commit is contained in:
Xiaotian Feng 2010-08-13 15:19:11 +08:00 committed by Avi Kivity
parent 3cfc2c42c1
commit f45755b834
2 changed files with 3 additions and 2 deletions
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1
arch/x86/kernel/i387.c
View File

@ -40,6 +40,7 @@
static unsigned int mxcsr_feature_mask __read_mostly = 0xffffffffu; static unsigned int mxcsr_feature_mask __read_mostly = 0xffffffffu;
unsigned int xstate_size; unsigned int xstate_size;
EXPORT_SYMBOL_GPL(xstate_size);
unsigned int sig_xstate_ia32_size = sizeof(struct _fpstate_ia32); unsigned int sig_xstate_ia32_size = sizeof(struct _fpstate_ia32);
static struct i387_fxsave_struct fx_scratch __cpuinitdata; static struct i387_fxsave_struct fx_scratch __cpuinitdata;

4
arch/x86/kvm/x86.c
View File

@ -2387,7 +2387,7 @@ static void kvm_vcpu_ioctl_x86_get_xsave(struct kvm_vcpu *vcpu,
if (cpu_has_xsave) if (cpu_has_xsave)
memcpy(guest_xsave->region, memcpy(guest_xsave->region,
&vcpu->arch.guest_fpu.state->xsave, &vcpu->arch.guest_fpu.state->xsave,
sizeof(struct xsave_struct)); xstate_size);
else { else {
memcpy(guest_xsave->region, memcpy(guest_xsave->region,
&vcpu->arch.guest_fpu.state->fxsave, &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) if (cpu_has_xsave)
memcpy(&vcpu->arch.guest_fpu.state->xsave, memcpy(&vcpu->arch.guest_fpu.state->xsave,
guest_xsave->region, sizeof(struct xsave_struct)); guest_xsave->region, xstate_size);
else { else {
if (xstate_bv & ~XSTATE_FPSSE) if (xstate_bv & ~XSTATE_FPSSE)
return -EINVAL; return -EINVAL;