linux-kernel - Re: [PATCH 3/4] um: net: Do not use drvdata in release

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Message-ID: <54288e93-c389-444c-afe4-bd099523bfab@cambridgegreys.com>
Date: Mon, 4 Nov 2024 16:54:25 +0000
From: Anton Ivanov <anton.ivanov@...bridgegreys.com>
To: Tiwei Bie <tiwei.btw@...group.com>, richard@....at,
 johannes@...solutions.net
Cc: linux-um@...ts.infradead.org, linux-kernel@...r.kernel.org,
 stable@...r.kernel.org
Subject: Re: [PATCH 3/4] um: net: Do not use drvdata in release



On 04/11/2024 16:32, Tiwei Bie wrote:
> The drvdata is not available in release. Let's just use container_of()
> to get the uml_net instance. Otherwise, removing a network device will
> result in a crash:
> 
> RIP: 0033:net_device_release+0x10/0x6f
> RSP: 00000000e20c7c40  EFLAGS: 00010206
> RAX: 000000006002e4e7 RBX: 00000000600f1baf RCX: 00000000624074e0
> RDX: 0000000062778000 RSI: 0000000060551c80 RDI: 00000000627af028
> RBP: 00000000e20c7c50 R08: 00000000603ad594 R09: 00000000e20c7b70
> R10: 000000000000135a R11: 00000000603ad422 R12: 0000000000000000
> R13: 0000000062c7af00 R14: 0000000062406d60 R15: 00000000627700b6
> Kernel panic - not syncing: Segfault with no mm
> CPU: 0 UID: 0 PID: 29 Comm: kworker/0:2 Not tainted 6.12.0-rc6-g59b723cd2adb #1
> Workqueue: events mc_work_proc
> Stack:
>   627af028 62c7af00 e20c7c80 60276fcd
>   62778000 603f5820 627af028 00000000
>   e20c7cb0 603a2bcd 627af000 62770010
> Call Trace:
>   [<60276fcd>] device_release+0x70/0xba
>   [<603a2bcd>] kobject_put+0xba/0xe7
>   [<60277265>] put_device+0x19/0x1c
>   [<60281266>] platform_device_put+0x26/0x29
>   [<60281e5f>] platform_device_unregister+0x2c/0x2e
>   [<6002ec9c>] net_remove+0x63/0x69
>   [<60031316>] ? mconsole_reply+0x0/0x50
>   [<600310c8>] mconsole_remove+0x160/0x1cc
>   [<60087d40>] ? __remove_hrtimer+0x38/0x74
>   [<60087ff8>] ? hrtimer_try_to_cancel+0x8c/0x98
>   [<6006b3cf>] ? dl_server_stop+0x3f/0x48
>   [<6006b390>] ? dl_server_stop+0x0/0x48
>   [<600672e8>] ? dequeue_entities+0x327/0x390
>   [<60038fa6>] ? um_set_signals+0x0/0x43
>   [<6003070c>] mc_work_proc+0x77/0x91
>   [<60057664>] process_scheduled_works+0x1b3/0x2dd
>   [<60055f32>] ? assign_work+0x0/0x58
>   [<60057f0a>] worker_thread+0x1e9/0x293
>   [<6005406f>] ? set_pf_worker+0x0/0x64
>   [<6005d65d>] ? arch_local_irq_save+0x0/0x2d
>   [<6005d748>] ? kthread_exit+0x0/0x3a
>   [<60057d21>] ? worker_thread+0x0/0x293
>   [<6005dbf1>] kthread+0x126/0x12b
>   [<600219c5>] new_thread_handler+0x85/0xb6
> 
> Cc: stable@...r.kernel.org
> Signed-off-by: Tiwei Bie <tiwei.btw@...group.com>
> ---
>   arch/um/drivers/net_kern.c | 2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/arch/um/drivers/net_kern.c b/arch/um/drivers/net_kern.c
> index 77c4afb8ab90..75d04fb4994a 100644
> --- a/arch/um/drivers/net_kern.c
> +++ b/arch/um/drivers/net_kern.c
> @@ -336,7 +336,7 @@ static struct platform_driver uml_net_driver = {
>   
>   static void net_device_release(struct device *dev)
>   {
> -	struct uml_net *device = dev_get_drvdata(dev);
> +	struct uml_net *device = container_of(dev, struct uml_net, pdev.dev);
>   	struct net_device *netdev = device->dev;
>   	struct uml_net_private *lp = netdev_priv(netdev);
>   
Acked-By: Anton Ivanov <anton.ivanov@...bridgegreys.com>
-- 
Anton R. Ivanov
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