[PATCH AUTOSEL 4.19 034/209] usb: gadget: udc: fotg210-udc: Fix a sleep-in-atomic-context bug in fotg210_get_status()

Sasha Levin
2019-11-13T02:26:54Z

From: Jia-Ju Bai <baijiaju1990@gmail.com>

[ Upstream commit 2337a77c1cc86bc4e504ecf3799f947659c86026 ]

The driver may sleep in an interrupt handler.
The function call path (from bottom to top) in Linux-4.17 is:

[FUNC] fotg210_ep_queue(GFP_KERNEL)
drivers/usb/gadget/udc/fotg210-udc.c, 744:
fotg210_ep_queue in fotg210_get_status
drivers/usb/gadget/udc/fotg210-udc.c, 768:
fotg210_get_status in fotg210_setup_packet
drivers/usb/gadget/udc/fotg210-udc.c, 949:
fotg210_setup_packet in fotg210_irq (interrupt handler)

To fix this bug, GFP_KERNEL is replaced with GFP_ATOMIC.
If possible, spin_unlock() and spin_lock() around fotg210_ep_queue()
can be also removed.

This bug is found by my static analysis tool DSAC.

Signed-off-by: Jia-Ju Bai <baijiaju1990@gmail.com>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/usb/gadget/udc/fotg210-udc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/usb/gadget/udc/fotg210-udc.c b/drivers/usb/gadget/udc/fotg210-udc.c
index 587c5037ff079..bc6abaea907d8 100644
--- a/drivers/usb/gadget/udc/fotg210-udc.c
+++ b/drivers/usb/gadget/udc/fotg210-udc.c
@@ -741,7 +741,7 @@ static void fotg210_get_status(struct fotg210_udc *fotg210,
fotg210->ep0_req->length = 2;

spin_unlock(&fotg210->lock);
- fotg210_ep_queue(fotg210->gadget.ep0, fotg210->ep0_req, GFP_KERNEL);
+ fotg210_ep_queue(fotg210->gadget.ep0, fotg210->ep0_req, GFP_ATOMIC);
spin_lock(&fotg210->lock);
}

--
2.20.1