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Re: breakpoint assistance: single-step out of line
On Fri, 2007-03-16 at 10:09 -0400, Frank Ch. Eigler wrote:
> Roland McGrath <roland@redhat.com> writes:
>
> > The method of single-stepping over an out of line copy of the
> > instruction clobbered by breakpoint insertion has been proven by
> > kprobes. The complexities are mitigated in that implementation by
> > the constrained context of the kernel and the fixed subset of
> > possible machine code known to validly occur in any kernel or module
> > text.
>
> Another important aspect is that userspace may be hostile. Beyond
> just containing oddball instruction sequences, it may deliberately
> rewrite its own .text, or otherwise interfere with probing in order to
> produce crashes or security breaches.
Under what circumstances can a user program rewrite its own text?
>
> - FChE
Jim