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From: Jeff Dike <jdike@addtoit.com>
To: WANG Cong <xiyou.wangcong@gmail.com>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org,
	user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [uml-devel] [PATCH 9/19] UML - Tidy ptrace interface
Date: Mon, 28 Apr 2008 11:42:40 -0400	[thread overview]
Message-ID: <20080428154240.GD7334@c2.user-mode-linux.org> (raw)
In-Reply-To: <20080426.173538.195417245.xiyou.wangcong@gmail.com>

On Sat, Apr 26, 2008 at 05:35:38PM +0800, WANG Cong wrote:
> From: Jeff Dike <jdike@addtoit.com>
> Date: Fri, 25 Apr 2008 13:56:10 -0400
> > Tidy the ptrace interface code.  Removed a bunch of unused macros.
> > Started converting register sets from arrays of longs to structures.
> 
> Could you please explain a bit why do this? I think long arrary is OK.

It's wrong on x86_64.  There, FRAME_SIZE is 168 -
     #define FRAME_SIZE 
and SS is the last register defined -
    #define SS 160
but there are a number of registers beyond that in the user_regs_struct:
	unsigned long	ss;
	unsigned long	fs_base;
	unsigned long	gs_base;
	unsigned long	ds;
	unsigned long	es;
	unsigned long	fs;
	unsigned long	gs;

The effect of GETREGS into a long[FRAME_SIZE] will be stack corruption.

    	      	      Jeff

-- 
Work email - jdike at linux dot intel dot com

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WARNING: multiple messages have this Message-ID (diff)
From: Jeff Dike <jdike@addtoit.com>
To: WANG Cong <xiyou.wangcong@gmail.com>
Cc: akpm@osdl.org, linux-kernel@vger.kernel.org,
	user-mode-linux-devel@lists.sourceforge.net
Subject: Re: [PATCH 9/19] UML - Tidy ptrace interface
Date: Mon, 28 Apr 2008 11:42:40 -0400	[thread overview]
Message-ID: <20080428154240.GD7334@c2.user-mode-linux.org> (raw)
In-Reply-To: <20080426.173538.195417245.xiyou.wangcong@gmail.com>

On Sat, Apr 26, 2008 at 05:35:38PM +0800, WANG Cong wrote:
> From: Jeff Dike <jdike@addtoit.com>
> Date: Fri, 25 Apr 2008 13:56:10 -0400
> > Tidy the ptrace interface code.  Removed a bunch of unused macros.
> > Started converting register sets from arrays of longs to structures.
> 
> Could you please explain a bit why do this? I think long arrary is OK.

It's wrong on x86_64.  There, FRAME_SIZE is 168 -
     #define FRAME_SIZE 
and SS is the last register defined -
    #define SS 160
but there are a number of registers beyond that in the user_regs_struct:
	unsigned long	ss;
	unsigned long	fs_base;
	unsigned long	gs_base;
	unsigned long	ds;
	unsigned long	es;
	unsigned long	fs;
	unsigned long	gs;

The effect of GETREGS into a long[FRAME_SIZE] will be stack corruption.

    	      	      Jeff

-- 
Work email - jdike at linux dot intel dot com

  reply	other threads:[~2008-04-28 15:42 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2008-04-25 17:56 [uml-devel] [PATCH 9/19] UML - Tidy ptrace interface Jeff Dike
2008-04-25 17:56 ` Jeff Dike
2008-04-26  9:35 ` [uml-devel] " WANG Cong
2008-04-26  9:35   ` WANG Cong
2008-04-28 15:42   ` Jeff Dike [this message]
2008-04-28 15:42     ` Jeff Dike
2008-04-29  8:14     ` [uml-devel] " WANG Cong
2008-04-29  8:14       ` WANG Cong

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