[PATCH 2/3] serial: 8250_mxpcie: fail the probe when a port cannot be registered

[Linmao Li]

When serial8250_register_8250_port() fails the loop only breaks out and
the probe still returns success.  The entries it did not reach keep the
zero devm_kzalloc() left there, and the entry that failed keeps a
negative error code.

mxpcie8250_remove() then feeds all of them to
serial8250_unregister_port(), which checks neither: line 0 unregisters a
port this driver does not own, and the negative line indexes
serial8250_ports[] out of bounds.

Fail the probe instead, unregistering the ports registered so far.

Fixes: 0481a041e956 ("serial: 8250: split Moxa PCIe serial board support out of 8250_pci")
Signed-off-by: Linmao Li <lilinmao@xxxxxxxxxx>
---
 drivers/tty/serial/8250/8250_mxpcie.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/serial/8250/8250_mxpcie.c b/drivers/tty/serial/8250/8250_mxpcie.c
index c0e3517d4e4ec..ddd02d5622ec4 100644
--- a/drivers/tty/serial/8250/8250_mxpcie.c
+++ b/drivers/tty/serial/8250/8250_mxpcie.c
@@ -570,14 +570,18 @@ static int mxpcie8250_probe(struct pci_dev *pdev, const struct pci_device_id *id
 		dev_dbg(dev, "Setup PCI port: port %lx, irq %d, type %d\n",
 			up.port.iobase, up.port.irq, up.port.iotype);
 
-		priv->port[i].line = serial8250_register_8250_port(&up);
-		if (priv->port[i].line < 0) {
+		ret = serial8250_register_8250_port(&up);
+		if (ret < 0) {
 			dev_err(dev,
 				"Couldn't register serial port %lx, irq %d, type %d, error %d\n",
 				up.port.iobase, up.port.irq,
-				up.port.iotype, priv->port[i].line);
-			break;
+				up.port.iotype, ret);
+			while (i--)
+				serial8250_unregister_port(priv->port[i].line);
+
+			return ret;
 		}
+		priv->port[i].line = ret;
 		priv->port[i].rx_trig_level = MOXA_PUART_RX_TRIG_DEFAULT;
 	}
 
-- 
2.25.1