Re: [PATCH 2.6] 2/3 Serio: possible race in handle_events

[Zwane Mwaikambo]

On Sat, 23 Aug 2003, Andrew Morton wrote:

> Dmitry Torokhov <dtor_core@xxxxxxxxxxxxx> wrote:
> >
> > Do you think we should introduce allocate_serio/free_serio pair for dynamically 
> >  allocated serios; free_serio would scan event_list and invalidate events that 
> >  refer to freed serio?
> 
> I don't understand the subsystem well enough to say.  But if we are
> receiving events which refer to an already-freed serio then something is
> very broken.  We should be draining all those events before allowing the
> original object to be freed up.
> 
> Let's wait for Vojtech's comments.

This sounds somewhat like;

http://bugzilla.kernel.org/show_bug.cgi?id=973

Jul 25 04:54:24 lap kernel: slab error in cache_free_debugcheck(): cache 
`size-32': double free, or memory before object was overwritten
Jul 25 04:54:24 lap kernel: Call Trace:
Jul 25 04:54:24 lap kernel:  [<c014f130>] kfree+0xf0/0x310
Jul 25 04:54:24 lap kernel:  [<c02540fc>] psmouse_disconnect+0x2c/0x40
Jul 25 04:54:24 lap kernel:  [<c02540fc>] psmouse_disconnect+0x2c/0x40
Jul 25 04:54:24 lap kernel:  [<c025560d>] serio_handle_events+0xad/0xc0
Jul 25 04:54:24 lap kernel:  [<c0255620>] serio_thread+0x0/0x100
Jul 25 04:54:24 lap kernel:  [<c0255665>] serio_thread+0x45/0x100
Jul 25 04:54:24 lap kernel:  [<c010a126>] work_resched+0x5/0x16
Jul 25 04:54:24 lap kernel:  [<c0255620>] serio_thread+0x0/0x100
Jul 25 04:54:24 lap kernel:  [<c0255620>] serio_thread+0x0/0x100
Jul 25 04:54:24 lap kernel:  [<c01073b9>] kernel_thread_helper+0x5/0xc
Jul 25 04:54:24 lap kernel:
Jul 25 04:54:24 lap kernel: slab error in cache_free_debugcheck(): cache 
`size-32': double free, or memory after  object was overwritten

Jul 25 04:54:24 lap kernel: Call Trace:
Jul 25 04:54:24 lap kernel:  [<c014f15e>] kfree+0x11e/0x310
Jul 25 04:54:24 lap kernel:  [<c02540fc>] psmouse_disconnect+0x2c/0x40
Jul 25 04:54:24 lap kernel:  [<c02540fc>] psmouse_disconnect+0x2c/0x40
Jul 25 04:54:24 lap kernel:  [<c025560d>] serio_handle_events+0xad/0xc0
Jul 25 04:54:24 lap kernel:  [<c0255620>] serio_thread+0x0/0x100
Jul 25 04:54:24 lap kernel:  [<c0255665>] serio_thread+0x45/0x100
Jul 25 04:54:24 lap kernel:  [<c010a126>] work_resched+0x5/0x16
Jul 25 04:54:24 lap kernel:  [<c0255620>] serio_thread+0x0/0x100
Jul 25 04:54:24 lap kernel:  [<c0255620>] serio_thread+0x0/0x100
Jul 25 04:54:24 lap kernel:  [<c01073b9>] kernel_thread_helper+0x5/0xc
Jul 25 04:54:24 lap kernel:
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