netdev - Re: [FIX NETLINK] properly check arguments to netlink

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Date:	Wed, 19 Sep 2007 09:16:00 +0200
From:	Holger Eitzenberger <holger@...eitzenberger.de>
To:	David Miller <davem@...emloft.net>
Cc:	netdev@...r.kernel.org
Subject: Re: [FIX NETLINK] properly check arguments to netlink_bind()

David Miller <davem@...emloft.net> writes:

>> > while going through going netlink code I found out that netlink_bind()
>> > does not properly check bind parameters.  I checked both 2.6.23-rc1 as
>> > well as 2.6.16.53, both are affected.

> Firstly, you patch compares the address _pointer_ against
> the minimum length.  That's obviously wrong.

True, the message send later fixed that.

> And if you check the call sites of the protocol ->bind() methods, they
> all use on-stack buffer for the address object which is at least
> MAX_SOCK_ADDR bytes in length so that the bind methods don't have to
> check the size if they don't want to.

Also true, but in that case you still end up accessing uninitialized
data.  Also note that e. g. inet_bind() checks explicitely for that and
it's not clear to me why netlink_bind() is different.  Maybe you just
help me figuring out.

Another point is that simply calling

 bind(nl_fd, (struct sockaddr *)&an_int, sizeof(int));

will not return EINVAL but depends on the randomn data after an_int.

   /holger

 
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