Re: [B.A.T.M.A.N.] [RFC v3 02/19] batman-adv: Prepare framework for mesh genl config

[Sven Eckelmann <sven@narfation.org>]

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On Monday, 7 January 2019 19.49.06 CET Linus Lüssing wrote:
[...]
> I seem to be able to trigger a null pointer dereference for this
> batadv_hardif_put() call here. With the following steps I end up
> with a primary_if == NULL:
> 
> $ batctl if add 1
> 
> root@Linus-Debian:~# batctl o
> Error - interface bat0 is not present or not a batman-adv interface
> root@Linus-Debian:~# batctl if add 1
> Error - interface does not exist: 1
> root@Linus-Debian:~# batctl o
> Killed
> root@Linus-Debian:~#
> root@Linus-Debian:~#
> root@Linus-Debian:~# batctl o

You can reproduce it easier with (destroy is only there to make sure that the 
bat0 is really empty before the originator dump):

    batctl if destroy
    batctl if create
    batctl o

The check before 

    	batadv_hardif_put(primary_if);

is missing. So it should actually be (like in the nla_put_failure case):

    	if (primary_if)
    		batadv_hardif_put(primary_if);


And "batctl if add" is basically a short version of:

   batctl if create
   batctl if add -M XXXX

And in your test, only the second part failed.

Kind regards,
	Sven

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