linux-kernel - [PATCH] acpi: close race in toshiba

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Date:	Fri, 28 Nov 2008 08:19:09 -0800
From:	Arjan van de Ven <arjan@...radead.org>
To:	linux-kernel@...r.kernel.org
Cc:	philipl@...rt.org, lenb@...nel.org, akpm@...ux-foundation.org
Subject: [PATCH] acpi: close race in toshiba_acpi driver


>From 5d8af90c16de14f5d27c9d0b63118277941ebb4e Mon Sep 17 00:00:00 2001
From: Arjan van de Ven <arjan@...ux.intel.com>
Date: Fri, 28 Nov 2008 08:14:14 -0800
Subject: [PATCH] acpi: close race in toshiba_acpi driver

the toshiba ACPI driver will, in a failure case, free the rfkill state
before stopping the polling timer that would use this state. More interesting,
in the same failure case handling, it calls the exit function, which also
frees the rfkill state, but after stopping the polling.

If the race happens, a NULL pointer is passed to rfkill_force_state()
which then causes a nice dereference.

Fix the race by just not doing the too-early freeing of the rfkill state.

This appears to be the cause of a hot issue on kerneloops.org; while I
have no solid evidence of that this patch will fix the issue, the race
appears rather real.

Signed-off-by: Arjan van de Ven <arjan@...ux.intel.com>
---
 drivers/acpi/toshiba_acpi.c |    2 --
 1 files changed, 0 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/toshiba_acpi.c b/drivers/acpi/toshiba_acpi.c
index 66aac06..25f531d 100644
--- a/drivers/acpi/toshiba_acpi.c
+++ b/drivers/acpi/toshiba_acpi.c
@@ -848,8 +848,6 @@ static int __init toshiba_acpi_init(void)
 	ret = input_register_polled_device(toshiba_acpi.poll_dev);
 	if (ret) {
 		printk(MY_ERR "unable to register kill-switch input device\n");
-		rfkill_free(toshiba_acpi.rfk_dev);
-		toshiba_acpi.rfk_dev = NULL;
 		toshiba_acpi_exit();
 		return ret;
 	}
-- 
1.6.0.4


-- 
Arjan van de Ven 	Intel Open Source Technology Centre
For development, discussion and tips for power savings, 
visit http://www.lesswatts.org
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