[PATCH] tty: serial: pch_uart: add check for pci_get_slot()

[Haoxiang Li]

Add check for pci_get_slot() to prevent a potetial
null pointer dereference in pch_request_dma().

Fixes: 8368d6a2b739 ("pch_uart: don't hardcode PCI slot to get DMA device")
Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Haoxiang Li <haoxiang_li2024@xxxxxxx>
---
 drivers/tty/serial/pch_uart.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/tty/serial/pch_uart.c b/drivers/tty/serial/pch_uart.c
index ba1fcd663fe2..6c9e596a14e7 100644
--- a/drivers/tty/serial/pch_uart.c
+++ b/drivers/tty/serial/pch_uart.c
@@ -678,6 +678,11 @@ static void pch_request_dma(struct uart_port *port)
 	/* Get DMA's dev information */
 	dma_dev = pci_get_slot(priv->pdev->bus,
 			PCI_DEVFN(PCI_SLOT(priv->pdev->devfn), 0));
+	if (!dma_dev) {
+		dev_err(priv->port.dev, "%s: failed to get DMA device\n",
+			__func__);
+		return;
+	}
 
 	/* Set Tx DMA */
 	param = &priv->param_tx;
-- 
2.25.1