[45/89] USB: cdc-wdm: updating desc->length must be protected by spin_lock

[Greg KH]

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Bjørn Mork <bj...@mork.no>

commit c428b70c1e115c5649707a602742e34130d19428 upstream.

wdm_in_callback() will also touch this field, so we cannot change it without 
locking

Signed-off-by: Bjørn Mork <bj...@mork.no>
Acked-by: Oliver Neukum <oneu...@suse.de>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 drivers/usb/class/cdc-wdm.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -467,7 +467,9 @@ retry:
        for (i = 0; i < desc->length - cntr; i++)
                desc->ubuf[i] = desc->ubuf[i + cntr];
 
+       spin_lock_irq(&desc->iuspin);
        desc->length -= cntr;
+       spin_unlock_irq(&desc->iuspin);
        /* in case we had outstanding data */
        if (!desc->length)
                clear_bit(WDM_READ, &desc->flags);


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