Commit 9494849e authored Jul 02, 2013 by Alexey Khoroshilov Committed by John W. Linville Jul 17, 2013

ath9k_htc: fix data race between request_firmware_nowait() callback and suspend()



ath9k_hif_usb_probe() requests firmware asynchronically and
there is some initialization postponed till firmware is ready.
In particular, ath9k_hif_usb_firmware_cb() callback initializes
hif_dev->tx.tx_buf and hif_dev->tx.tx_pending lists.

At the same time, ath9k_hif_usb_suspend() iterates that lists through
ath9k_hif_usb_dealloc_urbs(). If suspend happens before request_firmware_nowait()
callback is called, it can lead to oops.

Similar issue could be in ath9k_hif_usb_disconnect(), but it is prevented
using hif_dev->fw_done completion and HIF_USB_READY flag. The patch extends
this approach to suspend() as well.

Found by Linux Driver Verification project (linuxtesting.org).

Signed-off-by: Alexey Khoroshilov <khoroshilov@ispras.ru>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

parent a4943ccb

drivers/net/wireless/ath/ath9k/hif_usb.c

+6 −3

Original line number	Diff line number	Diff line
		@@ -1082,7 +1082,7 @@ static void ath9k_hif_usb_firmware_fail(struct hif_device_usb *hif_dev)
		struct device *dev = &hif_dev->udev->dev;
		struct device *parent = dev->parent;

		complete(&hif_dev->fw_done);
		complete_all(&hif_dev->fw_done);

		if (parent)
		device_lock(parent);
		@@ -1131,7 +1131,7 @@ static void ath9k_hif_usb_firmware_cb(const struct firmware fw, void context)

		release_firmware(fw);
		hif_dev->flags \|= HIF_USB_READY;
		complete(&hif_dev->fw_done);
		complete_all(&hif_dev->fw_done);

		return;

		@@ -1316,6 +1316,9 @@ static int ath9k_hif_usb_suspend(struct usb_interface *interface,
		if (!(hif_dev->flags & HIF_USB_START))
		ath9k_htc_suspend(hif_dev->htc_handle);

		wait_for_completion(&hif_dev->fw_done);

		if (hif_dev->flags & HIF_USB_READY)
		ath9k_hif_usb_dealloc_urbs(hif_dev);

		return 0;