Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752203Ab0HMVEN (ORCPT ); Fri, 13 Aug 2010 17:04:13 -0400 Received: from terminus.zytor.com ([198.137.202.10]:34762 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750847Ab0HMVEK (ORCPT ); Fri, 13 Aug 2010 17:04:10 -0400 Message-ID: <4C65B327.8020605@zytor.com> Date: Fri, 13 Aug 2010 14:03:35 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.7) Gecko/20100720 Fedora/3.1.1-1.fc13 Thunderbird/3.1.1 MIME-Version: 1.0 To: Xiaotian Feng , avi Kivity CC: x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Thomas Gleixner , Ingo Molnar , Suresh Siddha , Brian Gerst , Avi Kivity , Robert Richter , Sheng Yang , Marcelo Tosatti , Gleb Natapov , Jan Kiszka Subject: Re: [PATCH] kvm: fix poison overwritten caused by using wrong xstate size References: <1281683951-19814-1-git-send-email-dfeng@redhat.com> In-Reply-To: <1281683951-19814-1-git-send-email-dfeng@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2652 Lines: 69 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 > 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 > --- > 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; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/