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Date: Sun, 27 Feb 2011 21:50:00 -0000
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From: Mark Kettenis <mark.kettenis@xs4all.nl>
To: msnyder@vmware.com
CC: jan.kratochvil@redhat.com, gdb-patches@sourceware.org, dje@google.com
In-reply-to: <4D6AC1C3.10508@vmware.com> (message from Michael Snyder on Sun,	27 Feb 2011 13:27:31 -0800)
Subject: Re: [RFA] off by one array reference in i386-low.c/i386_show_dr
References: <4D698427.2050301@vmware.com> <20110227164646.GA15468@host1.dyn.jankratochvil.net> <4D6AC1C3.10508@vmware.com>
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> Date: Sun, 27 Feb 2011 13:27:31 -0800
> From: Michael Snyder <msnyder@vmware.com>
> 
> >> --- i386-low.c	1 Jan 2011 15:33:24 -0000	1.5
> >> +++ i386-low.c	26 Feb 2011 22:48:38 -0000
> > /* A macro to loop over all debug registers.  */
> > #define ALL_DEBUG_REGISTERS(i)  for (i = 0; i < DR_NADDR; i++)
> >> @@ -195,7 +195,7 @@ i386_show_dr (struct i386_debug_reg_stat
> >   ALL_DEBUG_REGISTERS(i)
> >     {
> >       printf_unfiltered ("\
> >>  \tDR%d: addr=0x%s, ref.count=%d  DR%d: addr=0x%s, ref.count=%d\n",
> >>  	      i, paddress (state->dr_mirror[i]),
> >>  	      state->dr_ref_count[i],
> >> -	      i + 1, paddress (state->dr_mirror[i + 1]),
> >> +	      i + 1, paddress (state->dr_mirror[i]),
> >>  	      state->dr_ref_count[i + 1]);
> >>        i++;
> >>      }
> > 
> > ->
> > 	CONTROL (DR7): 0000000000090101          STATUS (DR6): 0000000000004000
> > 	DR0: addr=0x0000000001c31f30, ref.count=1  DR1: addr=0x0000000000000000, ref.count=0
> > 	DR2: addr=0x0000000000000000, ref.count=0  DR3: addr=0x0000000000000000, ref.count=0
> > 
> > I do not see a bug there; still it could be better commented.
> 
> The bug is that when "i" is 3, "i + 1" is 4, and the array only runs
> from 0 to 3.

But i can't be 3.