USB: cdc-wdm: updating desc->length must be protected by spin_lock

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

Cc: stable@vger.kernel.org
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Acked-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 1c50baff7725..1f6b5c8394b4 100644
--- 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);