Re: [PATCH v0] nfc: nci: add flush_workqueue to prevent uaf

[patchwork-bot+netdevbpf]

Hello:

This patch was applied to netdev/net.git (master)
by David S. Miller <davem@xxxxxxxxxxxxx>:

On Wed, 13 Apr 2022 00:04:30 +0800 you wrote:
> Our detector found a concurrent use-after-free bug when detaching an
> NCI device. The main reason for this bug is the unexpected scheduling
> between the used delayed mechanism (timer and workqueue).
> 
> The race can be demonstrated below:
> 
> Thread-1                           Thread-2
>                                  | nci_dev_up()
>                                  |   nci_open_device()
>                                  |     __nci_request(nci_reset_req)
>                                  |       nci_send_cmd
>                                  |         queue_work(cmd_work)
> nci_unregister_device()          |
>   nci_close_device()             | ...
>     del_timer_sync(cmd_timer)[1] |
> ...                              | Worker
> nci_free_device()                | nci_cmd_work()
>   kfree(ndev)[3]                 |   mod_timer(cmd_timer)[2]
> 
> [...]

Here is the summary with links:
  - [v0] nfc: nci: add flush_workqueue to prevent uaf
    https://git.kernel.org/netdev/net/c/ef27324e2cb7

You are awesome, thank you!
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