Re: [PATCH] drivers: isdn: capi: Fix data-race bug

[David Miller]

From: madhuparnabhowmik10@xxxxxxxxx
Date: Wed, 22 Jul 2020 22:53:29 +0530

> From: Madhuparna Bhowmik <madhuparnabhowmik10@xxxxxxxxx>
> 
> In capi_init(), after register_chrdev() the file operation callbacks
> can be called. However capinc_tty_init() is called later.
> Since capiminors and capinc_tty_driver are initialized in
> capinc_tty_init(), their initialization can race with their usage
> in various callbacks like in capi_release().
> 
> Therefore, call capinc_tty_init() before register_chrdev to avoid
> such race conditions.
> 
> Found by Linux Driver Verification project (linuxtesting.org).
> 
> Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik10@xxxxxxxxx>

I agree with Arnd that this just exchanges one set of problems for
another.