linux-kernel - Re: [PATCH net] net: dsa: Fix stale cpu_switch reference after unbind then bind

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] [day] [month] [year] [list]

Message-Id: <20170604.225740.1710058828586611741.davem@davemloft.net>
Date:   Sun, 04 Jun 2017 22:57:40 -0400 (EDT)
From:   David Miller <davem@...emloft.net>
To:     f.fainelli@...il.com
Cc:     netdev@...r.kernel.org, andrew@...n.ch,
        vivien.didelot@...oirfairelinux.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH net] net: dsa: Fix stale cpu_switch reference after
 unbind then bind

From: Florian Fainelli <f.fainelli@...il.com>
Date: Fri,  2 Jun 2017 22:05:23 -0700

> Commit 9520ed8fb841 ("net: dsa: use cpu_switch instead of ds[0]")
> replaced the use of dst->ds[0] with dst->cpu_switch since that is
> functionally equivalent, however, we can now run into an use after free
> scenario after unbinding then rebinding the switch driver.
> 
> The use after free happens because we do correctly initialize
> dst->cpu_switch the first time we probe in dsa_cpu_parse(), then we
> unbind the driver: dsa_dst_unapply() is called, and we rebind again.
> dst->cpu_switch now points to a freed "ds" structure, and so when we
> finally dereference it in dsa_cpu_port_ethtool_setup(), we oops.
> 
> To fix this, simply set dst->cpu_switch to NULL in dsa_dst_unapply()
> which guarantees that we always correctly re-assign dst->cpu_switch in
> dsa_cpu_parse().
> 
> Fixes: 9520ed8fb841 ("net: dsa: use cpu_switch instead of ds[0]")
> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>

Applied and queued up for -stable, thanks.