wan/x25_asy: integer overflow in x25_asy_change_mtu()
authorDan Carpenter <dan.carpenter@oracle.com>
Thu, 17 Jul 2014 10:50:45 +0000 (13:50 +0300)
committerDavid S. Miller <davem@davemloft.net>
Thu, 17 Jul 2014 23:47:50 +0000 (16:47 -0700)
If "newmtu * 2 + 4" is too large then it can cause an integer overflow
leading to memory corruption.  Eric Dumazet suggests that 65534 is a
reasonable upper limit.

Btw, "newmtu" is not allowed to be a negative number because of the
check in dev_set_mtu(), so that's ok.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
drivers/net/wan/x25_asy.c

index 5895f19786919f6cfb36b97273a95bc1462d1c10..fa9fdfa128c1e6b732c74907fb43504c8ec2ad4c 100644 (file)
@@ -122,8 +122,12 @@ static int x25_asy_change_mtu(struct net_device *dev, int newmtu)
 {
        struct x25_asy *sl = netdev_priv(dev);
        unsigned char *xbuff, *rbuff;
-       int len = 2 * newmtu;
+       int len;
 
+       if (newmtu > 65534)
+               return -EINVAL;
+
+       len = 2 * newmtu;
        xbuff = kmalloc(len + 4, GFP_ATOMIC);
        rbuff = kmalloc(len + 4, GFP_ATOMIC);