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usb: musb_gadget: fix crash caused by dangling pointer
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commit 08f75bf upstream.

usb_ep_ops.disable must clear external copy of the endpoint descriptor,
otherwise musb crashes after loading/unloading several gadget modules
in a row:

Unable to handle kernel paging request at virtual address bf013730
pgd = c0004000
[bf013730] *pgd=8f26d811, *pte=00000000, *ppte=00000000
Internal error: Oops: 7 [#1]
Modules linked in: g_cdc [last unloaded: g_file_storage]
CPU: 0    Not tainted  (3.2.17 raspberrypi#647)
PC is at musb_gadget_enable+0x4c/0x24c
LR is at _raw_spin_lock_irqsave+0x4c/0x58
[<c027c030>] (musb_gadget_enable+0x4c/0x24c) from [<bf01b760>] (gether_connect+0x3c/0x19c [g_cdc])
[<bf01b760>] (gether_connect+0x3c/0x19c [g_cdc]) from [<bf01ba1c>] (ecm_set_alt+0x15c/0x180 [g_cdc])
[<bf01ba1c>] (ecm_set_alt+0x15c/0x180 [g_cdc]) from [<bf01ecd4>] (composite_setup+0x85c/0xac4 [g_cdc])
[<bf01ecd4>] (composite_setup+0x85c/0xac4 [g_cdc]) from [<c027b744>] (musb_g_ep0_irq+0x844/0x924)
[<c027b744>] (musb_g_ep0_irq+0x844/0x924) from [<c027a97c>] (musb_interrupt+0x79c/0x864)
[<c027a97c>] (musb_interrupt+0x79c/0x864) from [<c027aaa8>] (generic_interrupt+0x64/0x7c)
[<c027aaa8>] (generic_interrupt+0x64/0x7c) from [<c00797cc>] (handle_irq_event_percpu+0x28/0x178)
...

Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
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notaz authored and bwhacks committed Jun 19, 2012
1 parent d143f1c commit c022fe2
Showing 1 changed file with 1 addition and 0 deletions.
1 change: 1 addition & 0 deletions drivers/usb/musb/musb_gadget.c
Original file line number Diff line number Diff line change
Expand Up @@ -1234,6 +1234,7 @@ static int musb_gadget_disable(struct usb_ep *ep)
}

musb_ep->desc = NULL;
musb_ep->end_point.desc = NULL;

/* abort all pending DMA and requests */
nuke(musb_ep, -ESHUTDOWN);
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