netdev - Re: [PATCH net] net: bridge: validate the NUD_PERMANENT bit when adding an extern

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Message-ID: <20210809123238.pi26xjxraaczemne@skbuf>
Date:   Mon, 9 Aug 2021 12:32:39 +0000
From:   Vladimir Oltean <vladimir.oltean@....com>
To:     Ido Schimmel <idosch@...sch.org>
CC:     "nikolay@...dia.com" <nikolay@...dia.com>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Jiri Pirko <jiri@...nulli.us>, Roopa Prabhu <roopa@...dia.com>,
        "bridge@...ts.linux-foundation.org" 
        <bridge@...ts.linux-foundation.org>,
        syzkaller-bugs <syzkaller-bugs@...glegroups.com>,
        "syzbot+9ba1174359adba5a5b7c@...kaller.appspotmail.com" 
        <syzbot+9ba1174359adba5a5b7c@...kaller.appspotmail.com>
Subject: Re: [PATCH net] net: bridge: validate the NUD_PERMANENT bit when
 adding an extern_learn FDB entry

On Mon, Aug 09, 2021 at 03:16:40PM +0300, Ido Schimmel wrote:
> On Mon, Aug 02, 2021 at 02:17:30AM +0300, Vladimir Oltean wrote:
> > diff --git a/net/bridge/br.c b/net/bridge/br.c
> > index ef743f94254d..bbab9984f24e 100644
> > --- a/net/bridge/br.c
> > +++ b/net/bridge/br.c
> > @@ -166,7 +166,8 @@ static int br_switchdev_event(struct notifier_block *unused,
> >  	case SWITCHDEV_FDB_ADD_TO_BRIDGE:
> >  		fdb_info = ptr;
> >  		err = br_fdb_external_learn_add(br, p, fdb_info->addr,
> > -						fdb_info->vid, false);
> > +						fdb_info->vid,
> > +						fdb_info->is_local, false);
> 
> When 'is_local' was added in commit 2c4eca3ef716 ("net: bridge:
> switchdev: include local flag in FDB notifications") it was not
> initialized in all the call sites that emit
> 'SWITCHDEV_FDB_ADD_TO_BRIDGE' notification, so it can contain garbage.

Thanks for the report, I'll send a patch which adds a:

	memset(&info, 0, sizeof(info));

to all SWITCHDEV_FDB_*_TO_BRIDGE call sites.