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From: "Tian, Kevin" <kevin.tian@intel.com>
To: Sergey Dyasli <sergey.dyasli@citrix.com>
Cc: Andrew Cooper <Andrew.Cooper3@citrix.com>,
	"Nakajima, Jun" <jun.nakajima@intel.com>,
	"jbeulich@suse.com" <jbeulich@suse.com>,
	"xen-devel@lists.xen.org" <xen-devel@lists.xen.org>
Subject: Re: [PATCH v2 1/3] x86/vmx: introduce vmx_find_msr()
Date: Wed, 22 Feb 2017 08:40:55 +0000	[thread overview]
Message-ID: <AADFC41AFE54684AB9EE6CBC0274A5D190C43855@SHSMSX101.ccr.corp.intel.com> (raw)
In-Reply-To: <1487752669.4239.1.camel@citrix.com>

> From: Sergey Dyasli [mailto:sergey.dyasli@citrix.com]
> Sent: Wednesday, February 22, 2017 4:38 PM
> 
> > >
> > > -    for ( idx = 0; idx < *msr_count; idx++ )
> > > +    for ( idx = 0; (*msr_area)[idx].index <= msr && idx < *msr_count; idx++ )
> >
> > risk of out-of-boundary access.
> 
> How exactly out-of-bounds access is possible? The original condition
> 
>     idx < *msr_count
> 
> Is still being checked on each loop iteration.
> 

Isn't "(*msr_area[idx]).index <= msr" checked before "idx < *msr_count"?

So if idx==*msr_count, you first hit an out-of-boundary access...

I think we should change the condition order here.

Thanks
Kevin
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  reply	other threads:[~2017-02-22  8:40 UTC|newest]

Thread overview: 17+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-02-17 15:42 [PATCH v2 0/3] x86/vmx: fix for vmentry failure with TSX bits in LBR Sergey Dyasli
2017-02-17 15:42 ` [PATCH v2 1/3] x86/vmx: introduce vmx_find_msr() Sergey Dyasli
     [not found]   ` <AADFC41AFE54684AB9EE6CBC0274A5D190C40BC0@SHSMSX101.ccr.corp.intel.com>
2017-02-22  8:37     ` Sergey Dyasli
2017-02-22  8:40       ` Tian, Kevin [this message]
2017-02-22  8:45         ` Sergey Dyasli
2017-02-22 10:14           ` Jan Beulich
2017-02-17 15:42 ` [PATCH v2 2/3] x86/vmx: optimize vmx_read/write_guest_msr() Sergey Dyasli
2017-02-21  9:31   ` Tian, Kevin
2017-02-22 10:16   ` Jan Beulich
2017-02-17 15:42 ` [PATCH v2 3/3] x86/vmx: fix vmentry failure with TSX bits in LBR Sergey Dyasli
2017-02-21  9:13   ` Tian, Kevin
2017-02-21 11:25     ` Andrew Cooper
2017-02-22  2:56       ` Tian, Kevin
2017-02-22 10:26   ` Jan Beulich
2017-02-22 13:58     ` Sergey Dyasli
2017-02-22 14:04       ` Andrew Cooper
2017-02-22 14:13       ` Jan Beulich

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