linux-kernel - Re: [PATCH] [usb-serial] fix Ooops on uplug

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: <20090721172841.36b20638@lxorguk.ukuu.org.uk>
Date:	Tue, 21 Jul 2009 17:28:41 +0100
From:	Alan Cox <alan@...rguk.ukuu.org.uk>
To:	Daniel Mack <daniel@...aq.de>
Cc:	Alan Stern <stern@...land.harvard.edu>,
	Kernel development list <linux-kernel@...r.kernel.org>,
	USB list <linux-usb@...r.kernel.org>
Subject: Re: [PATCH] [usb-serial] fix Ooops on uplug

> It was, at least in my case. Did some printk debugging and it showed
> that the hangup callback was entered what freed the serial device.

Ok 
> 
> > > This is only a lockdep warning, and I don't understand its
> > > significance.  Even worse, when I plugged in a USB flash drive
> > > afterward this appeared:
> > 
> > Looks like something freed the resources but didn't hang up when the
> > disconnect occurred
> 
> Probably the real fix would be to let the tty layer know the device died
> from the hangup handler.

The hangup event means the physical hardware must no longer be touched so
that's already the case and we use it for a lot of things (from ISAPnP to
PCMCIA to USB).

The USB code does slightly misimplement it - it calls tty_hangup() in
usb_serial_disconnect when it should call tty_vhangup() as it needs the
event to be synchronous. That is the hangup of the tty should be done
before the USB layer can sneak off and free stuff.

I don't at this point see that as explaining the bug however
--
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/