netdev - Re: net-next kernel NULL pointer dereference at fib_rules

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Message-Id: <20120710.180543.1460678493453873565.davem@davemloft.net>
Date:	Tue, 10 Jul 2012 18:05:43 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	gregory.v.rose@...el.com
Cc:	eric.dumazet@...il.com, ogerlitz@...lanox.com,
	netdev@...r.kernel.org, shlomop@...lanox.com, amirv@...lanox.com,
	erezsh@...lanox.com
Subject: Re: net-next kernel NULL pointer dereference at fib_rules_tclass

From: Greg Rose <gregory.v.rose@...el.com>
Date: Tue, 10 Jul 2012 11:14:34 -0700

> On Tue, 10 Jul 2012 19:25:01 +0200
> Eric Dumazet <eric.dumazet@...il.com> wrote:
> 
>> On Tue, 2012-07-10 at 09:44 -0700, David Miller wrote:
>> > From: Or Gerlitz <ogerlitz@...lanox.com>
>> > Date: Tue, 10 Jul 2012 10:16:55 +0300
>> > 
>> > > Starting system logger: BUG: unable to handle kernel NULL pointer
>> > > dereference at 00000000000000ac IP: [<ffffffff81320393>]
>> > > fib_rules_tclass+0xf/0x17
>> > 
>> > Ok, fib_rules_tclass() checks for res->r being NULL and only
>> > dereferences it if it is not.
>> > 
>> > fib4_rule->tclassid has offset ~0x8c on x86-64, and this fault
>> > address is 0x10 bytes off.
>> > 
>> > Does this patch fix the problem?
>> > 
>> > diff --git a/include/net/ip_fib.h b/include/net/ip_fib.h
>> > index 539c672..000c467 100644
>> > --- a/include/net/ip_fib.h
>> > +++ b/include/net/ip_fib.h
>> > @@ -230,6 +230,7 @@ static inline int fib_lookup(struct net *net,
>> > struct flowi4 *flp, struct fib_result *res)
>> >  {
>> >  	if (!net->ipv4.fib_has_custom_rules) {
>> > +		res->r = NULL;
>> >  		if (net->ipv4.fib_local &&
>> >  		    !fib_table_lookup(net->ipv4.fib_local, flp,
>> > res, FIB_LOOKUP_NOREF))
>> 
>> It does here, thanks
> 
> Works for me too.

Great, pushed out to net-next, thanks everyone.
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