From: Stephen Hemminger <stephen@networkplumber.org>
To: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Cc: netdev@vger.kernel.org, roopa@cumulusnetworks.com,
davem@davemloft.net, bridge@lists.linux-foundation.org,
syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH net v3] net: bridge: fix vlan stats use-after-free on destruction
Date: Thu, 23 Apr 2020 17:05:21 -0700 [thread overview]
Message-ID: <20200423170521.65a3bc59@hermes.lan> (raw)
In-Reply-To: <20181116165001.30896-1-nikolay@cumulusnetworks.com>
On Fri, 16 Nov 2018 18:50:01 +0200
Nikolay Aleksandrov <nikolay@cumulusnetworks.com> wrote:
> Syzbot reported a use-after-free of the global vlan context on port vlan
> destruction. When I added per-port vlan stats I missed the fact that the
> global vlan context can be freed before the per-port vlan rcu callback.
> There're a few different ways to deal with this, I've chosen to add a
> new private flag that is set only when per-port stats are allocated so
> we can directly check it on destruction without dereferencing the global
> context at all. The new field in net_bridge_vlan uses a hole.
>
> v2: cosmetic change, move the check to br_process_vlan_info where the
> other checks are done
> v3: add change log in the patch, add private (in-kernel only) flags in a
> hole in net_bridge_vlan struct and use that instead of mixing
> user-space flags with private flags
>
> Fixes: 9163a0fc1f0c ("net: bridge: add support for per-port vlan stats")
> Reported-by: syzbot+04681da557a0e49a52e5@syzkaller.appspotmail.com
> Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Why not just use v->stats itself as the flag.
Since free of NULL is a nop it would be cleaner?
next prev parent reply other threads:[~2020-04-24 0:05 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-11-12 5:51 KASAN: use-after-free Read in nbp_vlan_rcu_free syzbot
2018-11-12 8:32 ` nikolay
2018-11-13 1:01 ` [PATCH net] net: bridge: fix per-port vlan stats use-after-free on destruction Nikolay Aleksandrov
2018-11-14 17:08 ` Nikolay Aleksandrov
2018-11-14 17:27 ` [PATCH net v2] net: bridge: fix " Nikolay Aleksandrov
2018-11-16 16:50 ` [PATCH net v3] " Nikolay Aleksandrov
2018-11-18 5:39 ` David Miller
2020-04-24 0:05 ` Stephen Hemminger [this message]
2020-04-24 7:26 ` Nikolay Aleksandrov
2020-05-20 15:50 ` Stephen Hemminger
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