[PATCH 4.4 240/268] serial: mxs-auart: Fix out-of-bounds access through serial port index

[Greg Kroah-Hartman]

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Geert Uytterhoeven <geert+rene...@glider.be>

[ Upstream commit dd345a31bfdec350d2593e6de5964e55c7f19c76 ]

The auart_port[] array is indexed using a value derived from the
"serialN" alias in DT, or from platform data, which may lead to an
out-of-bounds access.

Fix this by adding a range check.

Fixes: 1ea6607d4cdc9179 ("serial: mxs-auart: Allow device tree probing")
Signed-off-by: Geert Uytterhoeven <geert+rene...@glider.be>
Signed-off-by: Sasha Levin <alexander.le...@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/tty/serial/mxs-auart.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/drivers/tty/serial/mxs-auart.c
+++ b/drivers/tty/serial/mxs-auart.c
@@ -1274,6 +1274,10 @@ static int mxs_auart_probe(struct platfo
                s->port.line = pdev->id < 0 ? 0 : pdev->id;
        else if (ret < 0)
                return ret;
+       if (s->port.line >= ARRAY_SIZE(auart_port)) {
+               dev_err(&pdev->dev, "serial%d out of range\n", s->port.line);
+               return -EINVAL;
+       }
 
        if (of_id) {
                pdev->id_entry = of_id->data;