Re: [PATCH 9/19] UML - Tidy ptrace interface

[WANG Cong]

On Mon, 28 Apr 2008, Jeff Dike wrote:

> On Sat, Apr 26, 2008 at 05:35:38PM +0800, WANG Cong wrote:
> > From: Jeff Dike <jdike@xxxxxxxxxxx>
> > 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.

Thanks for teaching this. ;-)

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