Subject: Re: [PATCH 1/1] ehea: Fix use after free on reboot

From: Jan-Bernd Themann <[email-masked]>
Date: Tue, 20 May 2008 14:22:55 +0100

On Wednesday 14 May 2008 16:48, Brian King wrote:
> 
> Fixes the following use after free oops:
> 
> ehea: Reboot: freeing all eHEA resources
> Unable to handle kernel paging request for data at address 0x6b6b6b6b6b6b6c5b
> Faulting instruction address: 0xd000000000354488
> cpu 0x0: Vector: 300 (Data Access) at [c00000002ec6f310]
>     pc: d000000000354488: .ehea_shutdown_single_port+0x50/0x78 [ehea]
>     lr: d00000000035447c: .ehea_shutdown_single_port+0x44/0x78 [ehea]
>     sp: c00000002ec6f590
>    msr: 8000000000009032
>    dar: 6b6b6b6b6b6b6c5b
>  dsisr: 40000000
>   current = 0xc0000000281412e0
>   paca    = 0xc0000000006df300
>     pid   = 10930, comm = reboot
> enter ? for help
> [c00000002ec6f590] d00000000035d64c .ehea_remove+0x44/0x124 [ehea] (unreliable)
> [c00000002ec6f630] c000000000319f88 .of_platform_device_remove+0x40/0x58
> [c00000002ec6f6a0] c000000000291018 .__device_release_driver+0xb0/0xf0
> [c00000002ec6f730] c000000000291120 .driver_detach+0xc8/0xfc
> [c00000002ec6f7c0] c00000000028fe24 .bus_remove_driver+0xb4/0x114
> [c00000002ec6f850] c000000000291768 .driver_unregister+0x54/0x74
> [c00000002ec6f8e0] c00000000031a0c8 .of_unregister_driver+0x14/0x28
> [c00000002ec6f950] c000000000023ba0 .ibmebus_unregister_driver+0x10/0x24
> [c00000002ec6f9c0] d000000000354180 .ehea_reboot_notifier+0x30/0x4c [ehea]
> [c00000002ec6fa40] c0000000003c95a8 .notifier_call_chain+0x5c/0xcc
> [c00000002ec6fae0] c000000000082cd4 .__blocking_notifier_call_chain+0x70/0xb0
> [c00000002ec6fb90] c000000000075cf8 .kernel_restart_prepare+0x24/0x58
> [c00000002ec6fc10] c000000000075f0c .kernel_restart+0x20/0x6c
> [c00000002ec6fc90] c000000000078674 .sys_reboot+0x1d4/0x290
> [c00000002ec6fe30] c0000000000086ac syscall_exit+0x0/0x40
> --- Exception: c01 (System Call) at 000000000ff63a40
> SP (ffceea50) is in userspace
> 
> Signed-off-by: Brian King <[email-masked]>
> ---
> 
>  linux-2.6-bjking1/drivers/net/ehea/ehea_main.c |    3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff -puN drivers/net/ehea/ehea_main.c~ehea_useafter_free_fix drivers/net/ehea/ehea_main.c
> --- linux-2.6/drivers/net/ehea/ehea_main.c~ehea_useafter_free_fix	2008-05-14 09:38:10.000000000 -0500
> +++ linux-2.6-bjking1/drivers/net/ehea/ehea_main.c	2008-05-14 09:38:10.000000000 -0500
> @@ -3177,11 +3177,12 @@ out_err:
> 
>  static void ehea_shutdown_single_port(struct ehea_port *port)
>  {
> +	struct ehea_adapter *adapter = port->adapter;
>  	unregister_netdev(port->netdev);
>  	ehea_unregister_port(port);
>  	kfree(port->mc_list);
>  	free_netdev(port->netdev);
> -	port->adapter->active_ports--;
> +	adapter->active_ports--;
>  }
> 
>  static int ehea_setup_ports(struct ehea_adapter *adapter)
> _
> --
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> 

The patch looks good. 

Acked-by: Jan-Bernd Themann <[email-masked]>

Thanks,
Jan-Bernd