linux-kernel - Re: [PATCH] usbip:vudc: BUG kmalloc-2048 (Not tainted): Poison overwritten

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Date:   Thu, 18 Oct 2018 16:29:50 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     "Shuah Khan (Samsung OSG)" <shuah@...nel.org>,
        valentina.manea.m@...il.com, gregkh@...uxfoundation.org
Cc:     linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        stable@...r.kernel.org
Subject: Re: [PATCH] usbip:vudc: BUG kmalloc-2048 (Not tainted): Poison
 overwritten

On 10/18/18 9:19 AM, Shuah Khan (Samsung OSG) wrote:
> In rmmod path, usbip_vudc does platform_device_put() twice once from
> platform_device_unregister() and then from put_vudc_device().
> 
> The second put results in:
> 
> BUG kmalloc-2048 (Not tainted): Poison overwritten error or
> BUG: KASAN: use-after-free in kobject_put+0x1e/0x230 if KASAN is
> enabled.
> 
> [  169.042156] calling  init+0x0/0x1000 [usbip_vudc] @ 1697
> [  169.042396] =============================================================================
> [  169.043678] probe of usbip-vudc.0 returned 1 after 350 usecs
> [  169.044508] BUG kmalloc-2048 (Not tainted): Poison overwritten
> [  169.044509] -----------------------------------------------------------------------------
> ...
> [  169.057849] INFO: Freed in device_release+0x2b/0x80 age=4223 cpu=3 pid=1693
> [  169.057852] 	kobject_put+0x86/0x1b0
> [  169.057853] 	0xffffffffc0c30a96
> [  169.057855] 	__x64_sys_delete_module+0x157/0x240
> 
> Fix it to call platform_device_del() instead and let put_vudc_device() do
> the platform_device_put().
> 
> Reported-by: Randy Dunlap <rdunlap@...radead.org>
> Signed-off-by: Shuah Khan (Samsung OSG) <shuah@...nel.org>
> Cc: <stable@...r.kernel.org>

and
Tested-by: Randy Dunlap <rdunlap@...radead.org>

Thanks.

> ---
>  drivers/usb/usbip/vudc_main.c | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/usb/usbip/vudc_main.c b/drivers/usb/usbip/vudc_main.c
> index 3fc22037a82f..390733e6937e 100644
> --- a/drivers/usb/usbip/vudc_main.c
> +++ b/drivers/usb/usbip/vudc_main.c
> @@ -73,6 +73,10 @@ static int __init init(void)
>  cleanup:
>  	list_for_each_entry_safe(udc_dev, udc_dev2, &vudc_devices, dev_entry) {
>  		list_del(&udc_dev->dev_entry);
> +		/*
> +		 * Just do platform_device_del() here, put_vudc_device()
> +		 * calls the platform_device_put()
> +		 */
>  		platform_device_del(udc_dev->pdev);
>  		put_vudc_device(udc_dev);
>  	}
> @@ -89,7 +93,11 @@ static void __exit cleanup(void)
>  
>  	list_for_each_entry_safe(udc_dev, udc_dev2, &vudc_devices, dev_entry) {
>  		list_del(&udc_dev->dev_entry);
> -		platform_device_unregister(udc_dev->pdev);
> +		/*
> +		 * Just do platform_device_del() here, put_vudc_device()
> +		 * calls the platform_device_put()
> +		 */
> +		platform_device_del(udc_dev->pdev);
>  		put_vudc_device(udc_dev);
>  	}
>  	platform_driver_unregister(&vudc_driver);
> 


-- 
~Randy