linux-kernel - Re: [PATCH] kvm: Initialize all struct members to avoid stack information leak

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Date:	Tue, 19 Jul 2011 19:38:27 +0200
From:	Jan Kiszka <jan.kiszka@...mens.com>
To:	quintela@...hat.com
CC:	Marcus Meissner <meissner@...ell.com>, avi@...hat.com,
	mtosatti@...hat.com, tglx@...utronix.de, mingo@...hat.com,
	hpa@...or.com, x86@...nel.org, kvm@...r.kernel.org,
	linux-kernel@...r.kernel.org, Marcus Meissner <meissner@...e.de>
Subject: Re: [PATCH] kvm: Initialize all struct members to avoid stack information
 leak

On 2011-07-19 16:12, Juan Quintela wrote:
> Marcus Meissner <meissner@...ell.com> wrote:
>> Hi,
>>
>> Reported to us by Stephan Mueller of atsec.
>>
>> Several .pad struct members are not set to something, so they
>> will leak stack content back to user space.
>>
>> Ciao, Marcus
>>
>> Reported-by: Stephan Mueller <smueller@...ec.com>
>> Signed-off-by: Marcus Meissner <meissner@...e.de>
>> ---
>>  arch/x86/kvm/x86.c |    1 +
>>  1 files changed, 1 insertions(+), 0 deletions(-)
>>
>> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
>> index 77c9d86..621ffb6 100644
>> --- a/arch/x86/kvm/x86.c
>> +++ b/arch/x86/kvm/x86.c
>> @@ -3002,6 +3002,7 @@ long kvm_arch_vcpu_ioctl(struct file *filp,
>>  	case KVM_GET_VCPU_EVENTS: {
>>  		struct kvm_vcpu_events events;
>>  
>> +		memset(&events, 0, sizeof(events));
>>  		kvm_vcpu_ioctl_x86_get_vcpu_events(vcpu, &events);
>>  
>>  		r = -EFAULT;
> 
> Looking at arch/x86/include/asm/kvm.h & arch/x86/kvm/x86.c I can't see
> what pad fields are not initialized.  My reading is that everything is
> initialized in kvm_vcpu_ioctl_x86_get_vcpu_events().  What field are you
> refering to?

Good question. Information leaks were once addressed by 97e69aa62f, and
kvm_vcpu_events was not changed since then.

Jan

-- 
Siemens AG, Corporate Technology, CT T DE IT 1
Corporate Competence Center Embedded Linux
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