Re: ptrace.2: PTRACE_KILL needs a stopped process too

From: Pedro Alves
Date: Wed May 09 2012 - 18:08:23 EST

On 05/09/2012 09:12 PM, Oleg Nesterov wrote:

> tgkill() can kill the wrong process/thread too, although it lessens the risk.

> But I don't really understand the problem. The traced thread can't go away

> until the tracer does wait/detach, and thus its pid can't be reused?

There's the non-leader thread execs and tracer didn't enable
PTRACE_O_TRACEEXEC case at least, while you try to kill the thread that just
execed, I think. Though that's quite pedantic. The tracer could prevent this
in other ways.

> May be, "by accident" above means something else, not pid reuse...

Pffft, who writes buggy code anyway? ;-)

Pedro Alves
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