[PATCH 4.4 13/80] usb: gadget: r8a66597: Fix a possible sleep-in-atomic-context bugs in r8a66597_queue()

[Greg Kroah-Hartman]

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

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

From: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>

[ Upstream commit f36b507c14c4b6e634463a610294e9cb0065c8ea ]

The driver may sleep in an interrupt handler.
The function call path (from bottom to top) in Linux-4.16.7 is:

[FUNC] r8a66597_queue(GFP_KERNEL)
drivers/usb/gadget/udc/r8a66597-udc.c, 1193:
		r8a66597_queue in get_status
drivers/usb/gadget/udc/r8a66597-udc.c, 1301:
		get_status in setup_packet
drivers/usb/gadget/udc/r8a66597-udc.c, 1381:
		setup_packet in irq_control_stage
drivers/usb/gadget/udc/r8a66597-udc.c, 1508:
		irq_control_stage in r8a66597_irq (interrupt handler)

To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC.

This bug is found by my static analysis tool (DSAC-2) and checked by
my code review.

Signed-off-by: Jia-Ju Bai <baijiaju1990@xxxxxxxxx>
Signed-off-by: Felipe Balbi <felipe.balbi@xxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/usb/gadget/udc/r8a66597-udc.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/usb/gadget/udc/r8a66597-udc.c
+++ b/drivers/usb/gadget/udc/r8a66597-udc.c
@@ -1193,7 +1193,7 @@ __acquires(r8a66597->lock)
 	r8a66597->ep0_req->length = 2;
 	/* AV: what happens if we get called again before that gets through? */
 	spin_unlock(&r8a66597->lock);
-	r8a66597_queue(r8a66597->gadget.ep0, r8a66597->ep0_req, GFP_KERNEL);
+	r8a66597_queue(r8a66597->gadget.ep0, r8a66597->ep0_req, GFP_ATOMIC);
 	spin_lock(&r8a66597->lock);
 }