Re: [PATCH 17/24] serial: 8250_mxpcie: handle hangup during break

[sashiko-bot@kernel.org]

> From: Josef Bacik <josef@toxicpanda.com>
> 
> Ending a software break on a Moxa PCIe port in RS-485 2-wire mode
> dereferences a NULL tty pointer if the port was hung up while the break
> was being sent.
> 
> send_break() calls ->break_ctl(tty, -1), sleeps for the break duration
> and then calls ->break_ctl(tty, 0), without excluding a concurrent
> hangup. A hangup (a modem DCD drop, or the session leader exiting while
> another process of the session is in TCSBRK/TCSBRKP) runs uart_hangup(),
> which shuts the port down and clears port->state->port.tty. The second
> call still reaches mxpcie8250_software_break_ctl() through
> uart_break_ctl(), which then does:
> 
>     struct tty_struct *tty = port->state->port.tty;
> [ ... ]
> Cc: Crescent Hsieh <crescentcy.hsieh@moxa.com>
> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> Cc: Linmao Li <lilinmao@kylinos.cn>
> Signed-off-by: Josef Bacik <josef@toxicpanda.com>
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Sashiko has reviewed this patch and found no issues.

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Sashiko AI review · https://sashiko.dev/#/patchset/20261027-tty-llm-v1-0-99b0202ae546@linuxfoundation.org?part=17