[PATCH] usb: rtl8150: avoid using uninitialized CSCR value

[Morduan Zang]

Check get_registers() when reading CSCR in set_carrier().
If the control transfer fails, don't use the stack value.

Reported-by: syzbot+9db6c624635564ad813c@xxxxxxxxxxxxxxxxxxxxxxxxx
Closes: https://syzkaller.appspot.com/bug?extid=9db6c624635564ad813c
Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Morduan Zang <zhangdandan@xxxxxxxxxxxxx>
---
 drivers/net/usb/rtl8150.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/net/usb/rtl8150.c b/drivers/net/usb/rtl8150.c
index 4cda0643afb6..7e32726d3e6f 100644
--- a/drivers/net/usb/rtl8150.c
+++ b/drivers/net/usb/rtl8150.c
@@ -722,7 +722,11 @@ static void set_carrier(struct net_device *netdev)
 	rtl8150_t *dev = netdev_priv(netdev);
 	short tmp;
 
-	get_registers(dev, CSCR, 2, &tmp);
+	if (get_registers(dev, CSCR, 2, &tmp) < 0) {
+		netif_carrier_off(netdev);
+		return;
+	}
+
 	if (tmp & CSCR_LINK_STATUS)
 		netif_carrier_on(netdev);
 	else
-- 
2.50.1