linux-kernel - Re: Linux 2.6.28-rc2 i/o error on /dev/ttyUSB0

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]

Date:	Wed, 29 Oct 2008 13:28:42 +0100
From:	Helge Hafting <helge.hafting@...el.hist.no>
To:	Alan Cox <alan@...rguk.ukuu.org.uk>
CC:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: Linux 2.6.28-rc2 i/o error on /dev/ttyUSB0

Alan Cox wrote:
>> squarely in the "oops, kref's are screwed up" corner, and you should talk 
>> to Alan about your particular USB dongle. I bet that bisection would just 
>> show you one of the kref commits (eg 4a90f09b "tty: usb-serial krefs" or 
>> maybe 7d7b93c14 "tty: kref the tty driver object"). 
> 
> Doesn't sound like krefs but does sound like the tty layer changes
> somewhere.
> 
> Helge - can you get me an strace of this

I got "gpsd" out of the way - usually, this one is started
automatically by hotplug functionality.

Files attached:
1. dmesg right after inserting the pl2303, seems ok.
2. Then,
    strace cat /dev/ttyUSB0 > strace-cat-ttyUSB0
3. Nothing happened, so I interrupted with ^C. Then:
    strace cat /dev/ttyUSB0 > strace-cat-ttyUSB0-2
    This time I got an i/o error. Nothing in the dmesg log though.
4. Tried stracing gpsd, to see what happens when it tries
    read-only mode. It failed to open /dev/ttyUSB0, both regular and ro.
    Nothing special in dmesg.
5. Unplugged and replugged the gps unit. Tried a second strace of gpsd.
    It just failed to open /dev/ttyUSB0.
6. Another dmesg. Nothing much to see, other than the replugging.

The kernel warning seems harder to reproduce, but not the malfunctioning.

Helge Hafting



View attachment "strace-cat-ttyUSB0" of type "text/plain" (2203 bytes)

View attachment "strace-cat-ttyUSB0-2" of type "text/plain" (3919 bytes)

View attachment "dmesg-inserted-pl2303" of type "text/plain" (61912 bytes)

View attachment "strace-gpsd-ttyUSB0" of type "text/plain" (18387 bytes)

View attachment "dmesg2" of type "text/plain" (61855 bytes)