netdev - Re: [PATCH net 0/4] net/sched: forbid 'goto

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Message-Id: <20181022.194314.1462566480309700181.davem@davemloft.net>
Date:   Mon, 22 Oct 2018 19:43:14 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     dcaratti@...hat.com
Cc:     jiri@...nulli.us, xiyou.wangcong@...il.com, jhs@...atatu.com,
        netdev@...r.kernel.org
Subject: Re: [PATCH net 0/4] net/sched: forbid 'goto_chain' on fallback
 actions

From: Davide Caratti <dcaratti@...hat.com>
Date: Sat, 20 Oct 2018 23:33:06 +0200

> the following command:
> 
>  # tc actions add action police rate 1mbit burst 1k conform-exceed \
>  > pass / goto chain 42
> 
> generates a NULL pointer dereference when packets exceed the configured
> rate. Similarly, the following command:
> 
>  # tc actions add action pass random determ goto chain 42 2
> 
> makes the kernel crash with NULL dereference when the first packet does
> not match the 'pass' action.
> 
> gact and police allow users to specify a fallback control action, that is
> stored in the action private data. 'goto chain x' never worked for these
> cases, since a->goto_chain handle was never initialized. There is only one
> goto_chain handle per TC action, and it is designed to be non-NULL only if
> tcf_action contains a 'goto chain' command. So, let's forbid 'goto chain'
> on fallback actions.
> 
> Patch 1/4 and 2/4 change the .init() functions of police and gact, to let
> them return an error when users try to set 'goto chain x' in the fallback
> action. Patch 3/4 and 4/4 add TDC selftest coverage to this new behavior. 

Series applied.