linux-kernel - ipv4: detection of bootable network devices is broken in IP-Config

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Message-ID: <BLUPR0301MB153786F562E4CE806B4CB65090630@BLUPR0301MB1537.namprd03.prod.outlook.com>
Date:   Mon, 18 Sep 2017 14:42:31 +0000
From:   Steven Caron <steven.caron@...band.com>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: ipv4: detection of bootable  network devices is broken in  IP-Config

The procedure below from ipconfig.c assumes that "?" updates user_dev_name[0].
I think that falls under undefined use of the result as an lvalue.

It works when I explicitly assign the result of the operation back to user_dev_name[0].


static bool __init ic_is_init_dev(struct net_device *dev)
{
	if (dev->flags & IFF_LOOPBACK)
		return false;
	return user_dev_name[0] ? !strcmp(dev->name, user_dev_name) :
	    (!(dev->flags & IFF_LOOPBACK) &&
	     (dev->flags & (IFF_POINTOPOINT|IFF_BROADCAST)) &&
	     strncmp(dev->name, "dummy", 5));
}

Regards,

I guess booting from network is uncommon these days.

-Steven