[PATCH 4.9 005/164] char: lp: fix possible integer overflow in lp_setup()

[Greg Kroah-Hartman]

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

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

From: Willy Tarreau <w@xxxxxx>

commit 3e21f4af170bebf47c187c1ff8bf155583c9f3b1 upstream.

The lp_setup() code doesn't apply any bounds checking when passing
"lp=none", and only in this case, resulting in an overflow of the
parport_nr[] array. All versions in Git history are affected.

Reported-By: Roee Hay <roee.hay@xxxxxxx>
Cc: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Signed-off-by: Willy Tarreau <w@xxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/char/lp.c |    6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

--- a/drivers/char/lp.c
+++ b/drivers/char/lp.c
@@ -859,7 +859,11 @@ static int __init lp_setup (char *str)
 	} else if (!strcmp(str, "auto")) {
 		parport_nr[0] = LP_PARPORT_AUTO;
 	} else if (!strcmp(str, "none")) {
-		parport_nr[parport_ptr++] = LP_PARPORT_NONE;
+		if (parport_ptr < LP_NO)
+			parport_nr[parport_ptr++] = LP_PARPORT_NONE;
+		else
+			printk(KERN_INFO "lp: too many ports, %s ignored.\n",
+			       str);
 	} else if (!strcmp(str, "reset")) {
 		reset = 1;
 	}