Re: [PATCH v2 2/3] USB: cdc-acm: fix unprivileged TIOCCSERIAL

[Oliver Neukum]

Am Donnerstag, den 08.04.2021, 15:16 +0200 schrieb Johan Hovold:
> TIOCSSERIAL is a horrid, underspecified, legacy interface which for most
> serial devices is only useful for setting the close_delay and
> closing_wait parameters.
> 
> A non-privileged user has only ever been able to set the since long
> deprecated ASYNC_SPD flags and trying to change any other *supported*
> feature should result in -EPERM being returned. Setting the current
> values for any supported features should return success.
> 
> Fix the cdc-acm implementation which instead indicated that the
> TIOCSSERIAL ioctl was not even implemented when a non-privileged user
> set the current values.
> 
> Fixes: ba2d8ce9db0a ("cdc-acm: implement TIOCSSERIAL to avoid blocking close(2)")
> Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Acked-by: Oliver Neukum <oneukum@xxxxxxxx>