[PATCH] ARM: aout-core: zero thread debug registers in a.out core dump

[Bryan Wu]

On Thu, Mar 10, 2011 at 6:15 PM, Will Deacon <will.deacon at arm.com> wrote:

> Hi Bryan,
>
> > > Hi Bryan,
> > >
> > > Feel free to upgrade your tag on this (signed-off / acked) since this
> is
> > > clearly based on the patch you posted yesterday. I'd like to get this
> to
> > > Russell ASAP so that we don't get a build-breaker in the near future.
> > >
> >
> > Oh, I missed this email. Just send out an similar patch.
>
> No problem, I'd just like to get this in the pipeline asap!
>
> > > diff --git a/arch/arm/include/asm/a.out-core.h
> b/arch/arm/include/asm/a.out-core.h
> > > index 93d04ac..92f10cb 100644
> > > --- a/arch/arm/include/asm/a.out-core.h
> > > +++ b/arch/arm/include/asm/a.out-core.h
> > > @@ -32,11 +32,7 @@ static inline void aout_dump_thread(struct pt_regs
> *regs, struct user *dump)
> > >        dump->u_dsize = (tsk->mm->brk - tsk->mm->start_data + PAGE_SIZE
> - 1) >> PAGE_SHIFT;
> > >        dump->u_ssize = 0;
> > >
> > > -       dump->u_debugreg[0] = tsk->thread.debug.bp[0].address;
> > > -       dump->u_debugreg[1] = tsk->thread.debug.bp[1].address;
> > > -       dump->u_debugreg[2] = tsk->thread.debug.bp[0].insn.arm;
> > > -       dump->u_debugreg[3] = tsk->thread.debug.bp[1].insn.arm;
> > > -       dump->u_debugreg[4] = tsk->thread.debug.nsaved;
> > > +       memset(dump->u_debugreg, 0, sizeof(dump->u_debugreg));
> > >
> > I think this should be
> >  memset(dump->u_debugreg, 0, sizeof(dump->u_debugreg) * 8);
> >
> > u_debugreg is a pointer to a int, the array contains 8 of them as we
> > found in the user.h
>
> dump_udebugreg is an integer array of fixed size. If you look at
> the disassembly of fs/binfmt_aout.o (removed some inlining,
> recompiled with -01):
>
> 00000c7c <aout_dump_thread>:
>  c7c:   e92d4038        push    {r3, r4, r5, lr}
>  c80:   e1a05000        mov     r5, r0
>  c84:   e1a04001        mov     r4, r1
>  c88:   e1a0200d        mov     r2, sp
>
> [...]
>
>  cfc:   e2840090        add     r0, r4, #144    ; 0x90
>  d00:   e3a01020        mov     r1, #32
>  d04:   ebfffffe        bl      0 <__memzero>
>
> So the size from sizeof is correct, multiplying it by 8 is asking
> for trouble! If we used the ARRAY_SIZE macro, then the multiplication
> would be necessary because we would have performed the division inside
> the macro.
>
> Please can you submit another patch? I think the one I posted the other
> day was alright, so if you re-post that you can add my S-o-B.
>
> Thanks,
>
> Will
>
> Ah, yeah, I got it.

I think your patch is right, no need for me to repost. Please add my SOB

Signed-off-by: Bryan Wu <bryan.wu at canonical.com>

Thanks,
-Bryan
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