[lvc-project] [PATCH 1/2] tty: n_gsm: avoid reactivation without previous cleanup

[Dmitry Antipov]

On 7/6/26 5:35 PM, Greg Kroah-Hartman wrote:

> We've had loads of syzbot "issues" reported in this code, and unless it
> actually shows up in a real device or operation, I'd just leave it alone
> please as there are lots of subtle issues involved in it.
> 
> Have you tested this in real hardware?

No. But I don't see any practical reasons doing ioctl(..., GSMIOC_SETCONF_EXT, ...)
more than once (without GSM_FL_RESTART) without doing anything else. Worse, an
attempt to do it simultaneously from multiple threads is obviously racy.

> Why unlikely()?  Can you measure it with/without that?  If not, it
> should never be used.

See above. IIUC "real" userspace program which talks to the device is unlikely
to bomb the device driver with the weird sequences of ioctl()s like syzkaller
usually does.

Dmitry