linux-kernel - Re: Oops in usb-serial with keyspan adapter on current upstream

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Date:	Tue, 19 May 2009 10:39:18 -0400 (EDT)
From:	Alan Stern <stern@...land.harvard.edu>
To:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Linux Kernel list <linux-kernel@...r.kernel.org>,
	<linux-usb@...r.kernel.org>
Subject: Re: Oops in usb-serial with keyspan adapter on current upstream

On Tue, 19 May 2009, Benjamin Herrenschmidt wrote:

> So I can still reproduce it with today checkout
> (363383277081ce831642b72df40932ee05ce40a2).
> 
> Unable to handle kernel paging request for data at address 0x00000010
> Faulting instruction address: 0xc000000000301e0c
> Oops: Kernel access of bad area, sig: 11 [#1]
> SMP NR_CPUS=4 PowerMac
> Modules linked in: keyspan usbserial
> NIP: c000000000301e0c LR: c0000000002fb410 CTR: c0000000002fb29c
> REGS: c00000015a4e34c0 TRAP: 0300   Not tainted  (2.6.30-rc6-00065-g3633832)
> MSR: 9000000000009032 <EE,ME,IR,DR>  CR: 24000024  XER: 20000000
> DAR: 0000000000000010, DSISR: 0000000040000000
> TASK = c00000015a494950[170] 'khubd' THREAD: c00000015a4e0000 CPU: 1
> GPR00: c0000000008475e8 c00000015a4e3740 c000000000875430 0000000000000001 
> GPR04: 0000000000000000 c0000001581e2290 0000000000000001 0000000000000000 
> GPR08: 0000000000000000 0000000000000000 0000000000000000 c0000000002fb29c 
> GPR12: 0000000024000082 c0000000008a9480 0000000000000002 c0000001581dd230 
> GPR16: 00000000000003e8 0000000000000001 c0000001580b0800 c0000001581dd230 
> GPR20: 0000000000000000 0000000000000001 c0000001580b1800 0000000000000002 
> GPR24: c000000158226c00 c00000015811a780 c0000001581e2198 0000000000000000 
> GPR28: 0000000000000000 c00000015a4e37b0 c0000000007fede8 0000000000000000 
> NIP [c000000000301e0c] .release_nodes+0x54/0x254
> LR [c0000000002fb410] .device_del+0x174/0x1e8
> Call Trace:
> [c00000015a4e3740] [c00000015a4e3880] 0xc00000015a4e3880 (unreliable)
> [c00000015a4e37f0] [c0000000002fb410] .device_del+0x174/0x1e8
> [c00000015a4e3880] [d0000000005454dc] .usb_serial_disconnect+0xf8/0x1d0 [usbserial]
> [c00000015a4e3930] [c0000000003d1ed0] .usb_unbind_interface+0x7c/0x138
> [c00000015a4e39d0] [c0000000002fe77c] .__device_release_driver+0xb8/0x100
> [c00000015a4e3a60] [c0000000002fe930] .device_release_driver+0x30/0x54
> [c00000015a4e3af0] [c0000000002fd9c8] .bus_remove_device+0xe4/0x124
> [c00000015a4e3b80] [c0000000002fb404] .device_del+0x168/0x1e8
> [c00000015a4e3c10] [c0000000003cf08c] .usb_disable_device+0xa4/0x15c
> [c00000015a4e3cb0] [c0000000003c96ac] .usb_disconnect+0xc4/0x180
> [c00000015a4e3d60] [c0000000003ca794] .hub_thread+0x594/0x101c
> [c00000015a4e3f00] [c0000000000672b0] .kthread+0x80/0xcc
> [c00000015a4e3f90] [c00000000001fef0] .kernel_thread+0x54/0x70
> Instruction dump:
> ebc2a398 7c7a1b78 7c872378 39000000 3b800000 3be00000 38010070 f8010070 
> f8010078 7c1d0378 48000070 e81e8000 <e96a0010> e8840000 7fab0000 419e0014 
> ---[ end trace f9d8f1b68a9ea04d ]---
> 
> Pretty clearly a NULL dereference inside release_nodes() called by
> device_del(). After a bit of disassembly, it looks like the offending
> dereference is node->release (ie, node_to_group) called with a NULL node,
> so basically we got to a situation where cur == NULL in the first loop
> inside of remove_nodes() and it thus blows on
> 
> 	grp = node_to_group(node);
> 
> It also looks like first is NULL but it's unclear whether it is such
> as the result of first = first->next or the function was called that
> way, though I could try to figure it out with added debugging. It -does-
> seem that "cnt" might be 1 at the time of the crash.

It looks like dev->devres has been corrupted somehow.  As far as I can
tell, the keyspan driver doesn't touch it at all.  In fact, nothing in
drivers/usb/serial does.

> Do you need more data ?

The inner device_del() call comes from usb_serial_disconnect().  You 
could try adding some debugging there, to find out if dev->devres has 
been tampered with.

Alan Stern

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