linux-kernel - Re: [PATCH] make former thread ID available via PTRACE_GETEVENTMSG after PTRACE_EVENT

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Date:	Wed, 8 Jun 2011 20:20:32 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Denys Vlasenko <vda.linux@...glemail.com>
Cc:	Tejun Heo <tj@...nel.org>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] make former thread ID available via PTRACE_GETEVENTMSG
	after PTRACE_EVENT_EXEC stop

On 06/08, Denys Vlasenko wrote:
>
> Not sure what kind of locking, if any, I need to put around
> current->parent...

Yes ;)

> @@ -1383,8 +1383,10 @@ int search_binary_handler(struct linux_binprm *bprm,struct pt_regs *regs)
>  			 */
>  			bprm->recursion_depth = depth;
>  			if (retval >= 0) {
> -				if (depth == 0)
> -					tracehook_report_exec(fmt, bprm, regs);
> +				if (depth == 0) {
> +					pid_t pid = task_pid_nr_ns(current, task_active_pid_ns(current->parent));

It is not safe to use ->parent. At least you need rcu lock around.

Also. At this point current has already changed its pid, you should
record pid_t before ->load_binary().

And. We have the coding style police, please use scripts/checkpatch.pl



Just in case, I'll be off-line till Monday.

Oleg.

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