Re: 2.6.13-rc4 use after free in class_device_attr_show

From: Andrew Morton
Date: Mon Aug 01 2005 - 14:02:08 EST


Keith Owens <kaos@xxxxxxx> wrote:
>
> On Sat, 30 Jul 2005 02:29:55 -0700,
> Andrew Morton <akpm@xxxxxxxx> wrote:
> >Keith Owens <kaos@xxxxxxx> wrote:
> >>
> >> 2.6.13-rc4 + kdb, with lots of CONFIG_DEBUG options. There is an
> >> intermittent use after free in class_device_attr_show. Reboot with no
> >> changes and the problem does not always recur.
> >> ...
> >> ip is at class_device_attr_show+0x50/0xa0
> >> ...
> >
> >It might help to know which file is being read from here.
> >
> >The below patch will record the name of the most-recently-opened sysfs
> >file. You can print last_sysfs_file[] in the debugger or add the
> >appropriate printk to the ia64 code?
>
> No need for a patch. It is /dev/vcsa2.

You mean /sys/class/vc/vcsa2?

That appears to be using generic code...

Can you please summarise what you curently know about this bug? What is
being accessed after free in class_device_attr_show()? class_dev_attr?
cd?

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