linux-kernel - [PATCH 3.10 250/250] char: lp: fix possible integer overflow in lp

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Date:   Thu,  8 Jun 2017 01:00:36 +0200
From:   Willy Tarreau <w@....eu>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        linux@...ck-us.net
Cc:     Willy Tarreau <w@....eu>, Ben Hutchings <ben@...adent.org.uk>
Subject: [PATCH 3.10 250/250] char: lp: fix possible integer overflow in lp_setup()

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@....com>
Cc: Ben Hutchings <ben@...adent.org.uk>
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/char/lp.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/char/lp.c b/drivers/char/lp.c
index 0913d79..6b61910 100644
--- a/drivers/char/lp.c
+++ b/drivers/char/lp.c
@@ -857,7 +857,11 @@ 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;
 	}
-- 
2.8.0.rc2.1.gbe9624a