[PATCH net] ch9200: return error on failed register writes in ch9200_bind()

[Sergey Shtylyov]

The successful register writes, done via the USB control requests in
control_write(), seem vital for the normal functioning of the device,
however the driver's bind() method ignores error codes returned from
control_write().  Do bail out of ch9200_bind() on failed writes...

Found by Linux Verification Center (linuxtesting.org) with the Svace
static analysis tool.

Fixes: 4a476bd6d1d9 ("usbnet: New driver for QinHeng CH9200 devices")
Signed-off-by: Sergey Shtylyov <s.shtylyov@xxxxxxxxxxxx>

---
Changes in version 2:
- switched to checking for the negative error values instead of non-zero;
- added the Fixes tag, retargeting the patch to the net.git repo;
- dropped [RFT] from the subject.

 drivers/net/usb/ch9200.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/usb/ch9200.c b/drivers/net/usb/ch9200.c
index a206ffa76f1b..ab3cd3902ed7 100644
--- a/drivers/net/usb/ch9200.c
+++ b/drivers/net/usb/ch9200.c
@@ -360,32 +360,44 @@ static int ch9200_bind(struct usbnet *dev, struct usb_interface *intf)
 	data[1] = 0x0F;
 	retval = control_write(dev, REQUEST_WRITE, 0, MAC_REG_THRESHOLD, data,
 			       0x02, CONTROL_TIMEOUT_MS);
+	if (retval < 0)
+		return retval;
 
 	data[0] = 0xA0;
 	data[1] = 0x90;
 	retval = control_write(dev, REQUEST_WRITE, 0, MAC_REG_FIFO_DEPTH, data,
 			       0x02, CONTROL_TIMEOUT_MS);
+	if (retval < 0)
+		return retval;
 
 	data[0] = 0x30;
 	data[1] = 0x00;
 	retval = control_write(dev, REQUEST_WRITE, 0, MAC_REG_PAUSE, data,
 			       0x02, CONTROL_TIMEOUT_MS);
+	if (retval < 0)
+		return retval;
 
 	data[0] = 0x17;
 	data[1] = 0xD8;
 	retval = control_write(dev, REQUEST_WRITE, 0, MAC_REG_FLOW_CONTROL,
 			       data, 0x02, CONTROL_TIMEOUT_MS);
+	if (retval < 0)
+		return retval;
 
 	/* Undocumented register */
 	data[0] = 0x01;
 	data[1] = 0x00;
 	retval = control_write(dev, REQUEST_WRITE, 0, 254, data, 0x02,
 			       CONTROL_TIMEOUT_MS);
+	if (retval < 0)
+		return retval;
 
 	data[0] = 0x5F;
 	data[1] = 0x0D;
 	retval = control_write(dev, REQUEST_WRITE, 0, MAC_REG_CTRL, data, 0x02,
 			       CONTROL_TIMEOUT_MS);
+	if (retval < 0)
+		return retval;
 
 	retval = get_mac_address(dev, addr);
 	eth_hw_addr_set(dev->net, addr);
-- 
2.55.0