linux-kernel - Re: [RFC PATCH] set TASK_TRACED before arch

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Date:	Tue, 10 Jun 2008 16:23:28 +0800
From:	"Luming Yu" <luming.yu@...il.com>
To:	"Luck, Tony" <tony.luck@...el.com>
Cc:	"Roland McGrath" <roland@...hat.com>,
	"Petr Tesarik" <ptesarik@...e.cz>,
	LKML <linux-kernel@...r.kernel.org>, linux-ia64@...r.kernel.org
Subject: Re: [RFC PATCH] set TASK_TRACED before arch_ptrace code to fix a race

On Wed, Jun 4, 2008 at 5:31 AM, Luck, Tony <tony.luck@...el.com> wrote:
>> What do you mean by "extra"?  There is a SIGTRAP sent after execve
>> completes when ptraced, even when PTRACE_SYSCALL is not being used.
>> So for an execve that succeeds under PTRACE_SYSCALL, there is a
>> ptrace_notify at syscall entry, then a SIGTRAP queued (i.e., not seen
>> by ptrace if blocked), then a ptrace_notify at syscall exit.  If
>> that's what's happening (including the blocked SIGTRAP not being seen
>> by the ptracer, i.e. strace), then there is no mystery (and no bug).
>
> This might not be the same bug ... but I do have a definite 100%
> reproducible bug (latest git kernel, old version of strace (4.5.15-1.el4.1))
>
> Run:
>
>        $ strace -o logit -f make

For this test case, utrace doesn't work too..
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