From: Kangjie Lu <kjlu@umn.edu>
Date: Fri, 15 Mar 2019 17:16:06 +0000 (-0500)
Subject: tty: atmel_serial: fix a potential NULL pointer dereference
X-Git-Tag: v3.16.72~133
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=cf592ae629558dba003094192c667c74f4cc670c;p=thirdparty%2Fkernel%2Fstable.git

tty: atmel_serial: fix a potential NULL pointer dereference

commit c85be041065c0be8bc48eda4c45e0319caf1d0e5 upstream.

In case dmaengine_prep_dma_cyclic fails, the fix returns a proper
error code to avoid NULL pointer dereference.

Signed-off-by: Kangjie Lu <kjlu@umn.edu>
Fixes: 34df42f59a60 ("serial: at91: add rx dma support")
Acked-by: Richard Genoud <richard.genoud@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---

diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index bc1c68c926bd3..d8676716467b1 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -1045,6 +1045,10 @@ static int atmel_prepare_rx_dma(struct uart_port *port)
 				sg_dma_len(&atmel_port->sg_rx)/2,
 				DMA_DEV_TO_MEM,
 				DMA_PREP_INTERRUPT);
+	if (!desc) {
+		dev_err(port->dev, "Preparing DMA cyclic failed\n");
+		goto chan_err;
+	}
 	desc->callback = atmel_complete_rx_dma;
 	desc->callback_param = port;
 	atmel_port->desc_rx = desc;