linux-kernel - Re: [PATCH 2/2] exec: allow core_pipe recursion check to look for a value of 1 rather than 0 (v2)

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Date:	Sun, 31 Jan 2010 16:50:01 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Neil Horman <nhorman@...driver.com>
Cc:	linux-kernel@...r.kernel.org, akpm@...ux-foundation.org,
	jmoskovc@...hat.com, mingo@...hat.com, drbd-dev@...ts.linbit.com,
	benh@...nel.crashing.org, t.sailer@...mni.ethz.ch, abelay@....edu,
	gregkh@...e.de, spock@...too.org, viro@...iv.linux.org.uk,
	neilb@...e.de, mfasheh@...e.com, menage@...gle.com,
	shemminger@...ux-foundation.org, takedakn@...data.co.jp
Subject: Re: [PATCH 2/2] exec: allow core_pipe recursion check to look for
	a value of 1 rather than 0 (v2)

On 01/29, Neil Horman wrote:
>
>  void do_coredump(long signr, int exit_code, struct pt_regs *regs)
>  {
> ...
> -		if (call_usermodehelper_pipe(helper_argv[0], helper_argv, NULL,
> -				&cprm.file)) {
> +		cprm.file = NULL;

it is already NULL,

> +		if (call_usermodehelper_fns(helper_argv[0], helper_argv, NULL,
> +					    UMH_WAIT_EXEC, umh_pipe_setup,
> +					    NULL, &cprm)) {
> +			if (cprm.file)
> +				filp_close(cprm.file, NULL);

Hmm. Looks like this change fixes the bug by accident.

Before this patch, I think we leak info->stdin if kernel_thread() fails
in __call_usermodehelper() pathes.



Completely off-topic, but I think __call_usermodehelper(UMH_NO_WAIT) is
buggy. if kernel_thread() failes it should do call_usermodehelper_freeinfo().
Also, UMH_WAIT_EXEC should set ->retval in this case.

Cough. And why call_usermodehelper_exec() has this strange ->path[0] == '\0'
check?

Oleg.

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