From: Shuah Khan <skhan@linuxfoundation.org>
To: Zheng Wang <zyytlz.wz@163.com>, valentina.manea.m@gmail.com
Cc: gregkh@linuxfoundation.org, linux-usb@vger.kernel.org,
linux-kernel@vger.kernel.org, hackerzheng666@gmail.com,
1395428693sheep@gmail.com, alex000young@gmail.com,
Shuah Khan <skhan@linuxfoundation.org>
Subject: Re: [PATCH v3] usbip: vudc: Fix use after free bug in vudc_remove due to race condition
Date: Fri, 17 Mar 2023 16:53:07 -0600 [thread overview]
Message-ID: <d05ae776-ee19-2ce0-c06b-9825e5cbea82@linuxfoundation.org> (raw)
In-Reply-To: <20230317100954.2626573-1-zyytlz.wz@163.com>
On 3/17/23 04:09, Zheng Wang wrote:
> In vudc_probe, it calls init_vudc_hw, which bound &udc->timer with v_timer.
>
> When it calls usbip_sockfd_store, it will call v_start_timer to start the
> timer work.
>
> When we call vudc_remove to remove the driver, theremay be a sequence as
> follows:
>
> Fix it by shutdown the timer work before cleanup in vudc_remove.
>
> Note that removing a driver is a root-only operation, and should never
> happen. But the attacker can directly unplug the usb to trigger the remove
> function.
>
> CPU0 CPU1
>
> |v_timer
> vudc_remove |
> kfree(udc); |
> //free shost |
> |udc->gadget
> |//use
>
> The udc might be removed before v_timer finished, and UAF happens.
>
> This bug was found by Codeql static analysis and might by false positive.
This statement that this could be a false positive makes me hesitate
taking this patch.
What kind of testing have you done with this fix? Were you able to test
the scenario of unplugging usb?
thanks,
-- Shuah
next prev parent reply other threads:[~2023-03-17 22:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-17 10:09 [PATCH v3] usbip: vudc: Fix use after free bug in vudc_remove due to race condition Zheng Wang
2023-03-17 22:53 ` Shuah Khan [this message]
2023-03-18 7:39 ` Zheng Hacker
2023-04-13 8:09 ` Zheng Hacker
2023-04-13 18:01 ` Shuah Khan
2023-04-14 2:33 ` Zheng Hacker
-- strict thread matches above, loose matches on Subject: below --
2023-03-16 17:44 Zheng Wang
2023-03-16 17:47 ` Zheng Hacker
2023-03-16 17:57 ` Shuah Khan
2023-03-16 18:02 ` Zheng Hacker
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