Re: [PATCH] 2.4.0 i386 watchpoint problems

From: Andi Kleen (ak@suse.de)
Date: Fri Sep 22 2000 - 13:11:01 EST


On Fri, Sep 22, 2000 at 10:56:34AM -0700, Linus Torvalds wrote:
>
>
> On Fri, 22 Sep 2000, James Cownie wrote:
> >
> > This is obviously much better (getting a signal for ALL debug register
> > triggers is a _good_ thing), but is it safe to call force_sig_info
> > from the debug trap handler if it was entered from kernel mode ?
>
> Good question.

The behaviour is random unless you define a new si_code number or fix
SI_FROMUSER, see the queued SIGIO bug report thread you conveniently
ignored a few days ago.

The problem is that the !SI_FROMUSER check in bad_signal() does not work
properly, because SI_FROMUSER does not match the defined SI_* codes (it returns
true for kernel generated signals). The result is that it always looks at
current and what happens depends on the credentials of the current process
(= random)

-Andi
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