[PATCH 3.16 021/366] serial: mxs-auart: Fix out-of-bounds access through serial port index

[Ben Hutchings]

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

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

From: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>

commit dd345a31bfdec350d2593e6de5964e55c7f19c76 upstream.

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+renesas@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.16:
 - Explicitly clean up port on error
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 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
@@ -1050,6 +1050,11 @@ static int mxs_auart_probe(struct platfo
 		s->port.line = pdev->id < 0 ? 0 : pdev->id;
 	else if (ret < 0)
 		goto out_free;
+	if (s->port.line >= ARRAY_SIZE(auart_port)) {
+		dev_err(&pdev->dev, "serial%d out of range\n", s->port.line);
+		ret = -EINVAL;
+		goto out_free;
+	}
 
 	if (of_id) {
 		pdev->id_entry = of_id->data;