Re: Race in ptrace.

[Oleg Nesterov]

Salman Qazi wrote:
>
> A race in ptrace was pointed to us by a fellow Google engineer, Tavis
> Ormandy.  The race involves interaction between a tracer, a tracee and
> an antagonist.  The tracer is tracing the tracee with PTRACE_SYSCALL and
> waits on the tracee.  In the mean time, an antagonist blasts the tracee
> with SIGCONTs.

Could you please explain how did observe this race? Do you have a
test-case, or could you explain how we can reproduce it?

Because,

> It turns out that a SIGCONT wakes up the
> tracee in kernel mode,

SIGCONT must not wake up a TASK_TRACED task.


Yes, there are some know problems with SIGCONT && ptrace, but I don't
see anthing related to the described problem.

Thanks,

Oleg.

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