Re: [PATCH 03/10] ptrace: implement PTRACE_SEIZE
From: Tejun Heo
Date: Fri May 20 2011 - 05:07:30 EST
On Fri, May 20, 2011 at 12:00:17AM +0100, Pedro Alves wrote:
> > > UUIC, that opens a race where between SEIZEing and
> > > SETOPTIONS(O_TRACE FORK|VFORK|EXEC...), the tracee can
> > > fork/vfork/clone/exec, without the tracer getting the
> > > nice corresponding PTRACE_EVENT_ events.
Does it matter? The order of execution isn't even well defined
without synchronization border. If you want full synchronization, you
can INTERRUPT tracee.
> SEIZE,execvd,INTERRUPT (SETOPTS on interrupt)
> will make the tracer see a SIGTRAP that
> SEIZE,SETOPTS,execvd (SETOPTS on interrupt)
> would cause, isn't it?
Yes, SIGTRAP on exec(2) is nasty but also is scheduled to be removed
> Now, if it were possible for the tracer to set the
> default OPTS _before_ PTRACE_ATTACH/PTRACE_SEIZE...
I don't see why that would be necessary.
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