linux-kernel - Re: WARNING in dev_vprintk

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Message-ID: <1526300027.8070.0.camel@sipsolutions.net>
Date:   Mon, 14 May 2018 14:13:47 +0200
From:   Johannes Berg <johannes@...solutions.net>
To:     Eric Biggers <ebiggers3@...il.com>, linux-wireless@...r.kernel.org
Cc:     syzbot <syzbot+e64565577af34b3768dc@...kaller.appspotmail.com>,
        gregkh@...uxfoundation.org, linux-kernel@...r.kernel.org,
        syzkaller-bugs@...glegroups.com
Subject: Re: WARNING in dev_vprintk_emit

On Sun, 2018-05-13 at 11:47 -0700, Eric Biggers wrote:

> The bug is that mac80211_hwsim allows creating device names that are too long,
> via HWSIM_CMD_NEW_RADIO.  Commit a7cfebcb7594a2 ("cfg80211: limit wiphy names to
> 128 bytes") limited them to 128 bytes, but it's not enough because
> dev_vprintk_emit() needs the device name plus some other stuff to not exceed 128
> bytes.  Here's a reproducer that works on Linus' tree (commit ccda3c4b777),
> provided that CONFIG_MAC80211_HWSIM=y.  Note that you'll probably need to change
> the hardcoded MAC80211_HWSIM generic netlink family ID for it to work.
> Johannes, what would you say about limiting the name length to 64 bytes instead?

Don't really have any objections - care to send a patch?

johannes