ax25: Fix ax25_cb refcounting in ax25_ctl_ioctl

Use ax25_cb_put after ax25_find_cb in ax25_ctl_ioctl.
Reported-by: Bernard Pidoux F6BVP <f6bvp@free.fr>
Signed-off-by: Jarek Poplawski <jarkao2@gmail.com>
Reviewed-by: Ralf Baechle <ralf@linux-mips.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ax25/af_ax25.c

@@ -358,6 +358,7 @@ static int ax25_ctl_ioctl(const unsigned int cmd, void __user *arg)
 	ax25_dev *ax25_dev;
 	ax25_cb *ax25;
 	unsigned int k;
+	int ret = 0;
 
 	if (copy_from_user(&ax25_ctl, arg, sizeof(ax25_ctl)))
 		return -EFAULT;
@@ -388,57 +389,63 @@ static int ax25_ctl_ioctl(const unsigned int cmd, void __user *arg)
 	case AX25_WINDOW:
 		if (ax25->modulus == AX25_MODULUS) {
 			if (ax25_ctl.arg < 1 || ax25_ctl.arg > 7)
-				return -EINVAL;
+				goto einval_put;
 		} else {
 			if (ax25_ctl.arg < 1 || ax25_ctl.arg > 63)
-				return -EINVAL;
+				goto einval_put;
 		}
 		ax25->window = ax25_ctl.arg;
 		break;
 
 	case AX25_T1:
 		if (ax25_ctl.arg < 1)
-			return -EINVAL;
+			goto einval_put;
 		ax25->rtt = (ax25_ctl.arg * HZ) / 2;
 		ax25->t1  = ax25_ctl.arg * HZ;
 		break;
 
 	case AX25_T2:
 		if (ax25_ctl.arg < 1)
-			return -EINVAL;
+			goto einval_put;
 		ax25->t2 = ax25_ctl.arg * HZ;
 		break;
 
 	case AX25_N2:
 		if (ax25_ctl.arg < 1 || ax25_ctl.arg > 31)
-			return -EINVAL;
+			goto einval_put;
 		ax25->n2count = 0;
 		ax25->n2 = ax25_ctl.arg;
 		break;
 
 	case AX25_T3:
 		if (ax25_ctl.arg < 0)
-			return -EINVAL;
+			goto einval_put;
 		ax25->t3 = ax25_ctl.arg * HZ;
 		break;
 
 	case AX25_IDLE:
 		if (ax25_ctl.arg < 0)
-			return -EINVAL;
+			goto einval_put;
 		ax25->idle = ax25_ctl.arg * 60 * HZ;
 		break;
 
 	case AX25_PACLEN:
 		if (ax25_ctl.arg < 16 || ax25_ctl.arg > 65535)
-			return -EINVAL;
+			goto einval_put;
 		ax25->paclen = ax25_ctl.arg;
 		break;
 
 	default:
-		return -EINVAL;
+		goto einval_put;
 	  }
 
-	return 0;
+out_put:
+	ax25_cb_put(ax25);
+	return ret;
+
+einval_put:
+	ret = -EINVAL;
+	goto out_put;
 }
 
 static void ax25_fillin_cb_from_dev(ax25_cb *ax25, ax25_dev *ax25_dev)