linux-kernel - Re: [PATCH net] net: dsa: don't assign an error value to tag

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CAFSKS=NRMMz5u9qjFmhrxZMCVpa2ZP1jTJ5o+eUA6H2B2aotOg@mail.gmail.com>
Date:   Mon, 22 Mar 2021 15:51:08 -0500
From:   George McCollister <george.mccollister@...il.com>
To:     Vladimir Oltean <olteanv@...il.com>
Cc:     Andrew Lunn <andrew@...n.ch>,
        Vivien Didelot <vivien.didelot@...il.com>,
        Florian Fainelli <f.fainelli@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>, netdev@...r.kernel.org,
        open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH net] net: dsa: don't assign an error value to tag_ops

On Mon, Mar 22, 2021 at 3:46 PM Vladimir Oltean <olteanv@...il.com> wrote:
>
> On Mon, Mar 22, 2021 at 03:26:50PM -0500, George McCollister wrote:
> > Use a temporary variable to hold the return value from
> > dsa_tag_driver_get() instead of assigning it to dst->tag_ops. Leaving
> > an error value in dst->tag_ops can result in deferencing an invalid
> > pointer when a deferred switch configuration happens later.
> >
> > Fixes: 357f203bb3b5 ("net: dsa: keep a copy of the tagging protocol in the DSA switch tree")
> >
> > Signed-off-by: George McCollister <george.mccollister@...il.com>
> > ---
>
> Who dereferences the invalid pointer? dsa_tree_free I guess?

I saw it occur just above on the following line the next time
dsa_port_parse_cpu() is called:
if (dst->tag_ops->proto != tag_protocol) {

-George