linux-kernel - Re: kernel BUG and freeze on cat /proc/tty/driver/serial

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20120525000934.78136313@pyramind.ukuu.org.uk>
Date:	Fri, 25 May 2012 00:09:34 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Zdenek Kabelac <zdenek.kabelac@...il.com>
Cc:	Chuck Ebbert <cebbert@...hat.com>,
	"Mario 'BitKoenig' Holbe" <Mario.Holbe@...ilmenau.de>,
	linux-kernel@...r.kernel.org
Subject: Re: kernel BUG and freeze on cat /proc/tty/driver/serial

> -       struct tty_ldisc *ld = tty_ldisc_ref(port->tty);
> +       struct tty_ldisc *ld = port ? tty_ldisc_ref(port->tty) : NULL;
>         struct pps_event_time ts;
> 
>         if (ld && ld->ops->dcd_change)
> @@ -2465,7 +2465,7 @@ void uart_handle_dcd_change(struct uart_port
> *uport, unsigned int status)
>                 hardpps();
>  #endif
> 
> -       if (port->flags & ASYNC_CHECK_CD) {
> +       if (port && port->flags & ASYNC_CHECK_CD) {
>                 if (status)
>                         wake_up_interruptible(&port->open_wait);
>                 else if (port->tty)

Probably should be using tty krefs for this

	tty = tty_port_tty_get( ..) /  tty_kref_put

etc, and yes the NULL check is needed. The reference is needed so the tty
can't be freed under you.



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/