netdev - Re: [PATCHv2 net] net: sched: fix NULL pointer dereference when action calls some targets

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Message-ID: <20170818082934.GA1406@salvia>
Date:   Fri, 18 Aug 2017 10:29:34 +0200
From:   Pablo Neira Ayuso <pablo@...filter.org>
To:     Xin Long <lucien.xin@...il.com>
Cc:     network dev <netdev@...r.kernel.org>, davem@...emloft.net,
        Cong Wang <xiyou.wangcong@...il.com>
Subject: Re: [PATCHv2 net] net: sched: fix NULL pointer dereference when
 action calls some targets

On Fri, Aug 18, 2017 at 11:01:36AM +0800, Xin Long wrote:
> As we know in some target's checkentry it may dereference par.entryinfo
> to check entry stuff inside. But when sched action calls xt_check_target,
> par.entryinfo is set with NULL. It would cause kernel panic when calling
> some targets.
> 
> It can be reproduce with:
>   # tc qd add dev eth1 ingress handle ffff:
>   # tc filter add dev eth1 parent ffff: u32 match u32 0 0 action xt \
>     -j ECN --ecn-tcp-remove
> 
> It could also crash kernel when using target CLUSTERIP or TPROXY.
> 
> By now there's no proper value for par.entryinfo in ipt_init_target,
> but it can not be set with NULL. This patch is to void all these
> panics by setting it with an ipt_entry obj with all members = 0.
> 
> Note that this issue has been there since the very beginning.
> 
> Signed-off-by: Xin Long <lucien.xin@...il.com>

Acked-by: Pablo Neira Ayuso <pablo@...filter.org>