Re: 2.6.17-mm4

[Ingo Molnar]

* Dave Jones <davej@xxxxxxxxxx> wrote:

> On Thu, Jun 29, 2006 at 10:39:33PM +0200, Michal Piotrowski wrote:
> 
>  > This looks very strange.
>  > 
>  > BUG: unable to handle kernel paging request at virtual address 6b6b6c07
> 
> Looks like a use after free.

i'm too hunting use-after-free bugs - the ones fixed below fix certain 
crashes, but i'm still seeing a nasty one.

the crash is independent on lockdep enabled or disabled. See:

  http://redhat.com/~mingo/misc/

for the config and the crash.log.

	Ingo

-----------------
Subject: fix platform_device_put/del mishaps
From: Ingo Molnar <mingo@xxxxxxx>

this fixes drivers/char/pc8736x_gpio.c and drivers/char/scx200_gpio.c
to use the platform_device_del/put ops correctly.

Signed-off-by: Ingo Molnar <mingo@xxxxxxx>
---
 drivers/char/pc8736x_gpio.c |    5 +++--
 drivers/char/scx200_gpio.c  |    6 +++---
 2 files changed, 6 insertions(+), 5 deletions(-)

Index: linux/drivers/char/pc8736x_gpio.c
===================================================================
--- linux.orig/drivers/char/pc8736x_gpio.c
+++ linux/drivers/char/pc8736x_gpio.c
@@ -319,9 +319,10 @@ static int __init pc8736x_gpio_init(void
 	return 0;
 
 undo_platform_dev_add:
-	platform_device_put(pdev);
+	platform_device_del(pdev);
 undo_platform_dev_alloc:
-	kfree(pdev);
+	platform_device_put(pdev);
+
 	return rc;
 }
 
Index: linux/drivers/char/scx200_gpio.c
===================================================================
--- linux.orig/drivers/char/scx200_gpio.c
+++ linux/drivers/char/scx200_gpio.c
@@ -126,9 +126,10 @@ static int __init scx200_gpio_init(void)
 undo_chrdev_region:
 	unregister_chrdev_region(dev, num_pins);
 undo_platform_device_add:
-	platform_device_put(pdev);
+	platform_device_del(pdev);
 undo_malloc:
-	kfree(pdev);
+	platform_device_put(pdev);
+
 	return rc;
 }
 
@@ -136,7 +137,6 @@ static void __exit scx200_gpio_cleanup(v
 {
 	kfree(scx200_devices);
 	unregister_chrdev_region(MKDEV(major, 0), num_pins);
-	platform_device_put(pdev);
 	platform_device_unregister(pdev);
 	/* kfree(pdev); */
 }
-
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