linux-kernel - Re: [PATCH] (2.4.25 material?) Fix unbalanced helper

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Date:	Thu, 17 Jan 2008 19:02:43 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	nigel@...el.suspend2.net
Cc:	LKML <linux-kernel@...r.kernel.org>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	TuxOnIce-devel <tuxonice-devel@...ts.tuxonice.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Pavel Machek <pavel@....cz>
Subject: Re: [PATCH] (2.4.25 material?) Fix unbalanced helper_lock in kernel/kmod.c

On Thursday, 17 of January 2008, Nigel Cunningham wrote:
> Hi all.

Hi,

> First up, sorry for not inlining the patch - trouble with line wrapping.

No big deal.

> In 2.6.24-rc8, call_usermodehelper_exec has an exit path that can leave
> the helper_lock() call at the top of the routine unbalanced. The
> attached patch fixes this issue.

Thanks a lot for the patch (reproduced below), I think it's 2.6.24 material.
Andrew?

> Signed-off-by: Nigel Cunningham <nigel@...onice.net>

---
From: Nigel Cunningham <nigel@...onice.net>

In 2.6.24-rc8, call_usermodehelper_exec has an exit path that can leave
the helper_lock() call at the top of the routine unbalanced.  Fix it.

Signed-off-by: Nigel Cunningham <nigel@...onice.net>
Signed-off-by: Rafael J. Wysocki <rjw@...k.pl>
---
diff --git a/kernel/kmod.c b/kernel/kmod.c
index c6a4f8a..de27e15 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -468,8 +468,10 @@ int call_usermodehelper_exec(struct subprocess_info *sub_info,
 	sub_info->wait = wait;
 
 	queue_work(khelper_wq, &sub_info->work);
-	if (wait == UMH_NO_WAIT) /* task has freed sub_info */
+	if (wait == UMH_NO_WAIT) { /* task has freed sub_info */
+		helper_unlock();
 		return 0;
+	}
 	wait_for_completion(&done);
 	retval = sub_info->retval;
 

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