netdev - Re: Possible netfilter-related memory corruption in 2.6.37

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <1298056495.2425.26.camel@edumazet-laptop>
Date:	Fri, 18 Feb 2011 20:14:55 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Patrick McHardy <kaber@...sh.net>
Cc:	Jan Engelhardt <jengelh@...ozas.de>, Avi Kivity <avi@...hat.com>,
	netfilter-devel@...r.kernel.org,
	Marcelo Tosatti <mtosatti@...hat.com>,
	nicolas prochazka <prochazka.nicolas@...il.com>,
	KVM list <kvm@...r.kernel.org>, netdev <netdev@...r.kernel.org>
Subject: Re: Possible netfilter-related memory corruption in 2.6.37

Le vendredi 18 février 2011 à 19:37 +0100, Patrick McHardy a écrit :
> Am 14.02.2011 17:52, schrieb Patrick McHardy:
> > Am 14.02.2011 17:48, schrieb Eric Dumazet:
> >> I am not sure, but I guess nf_reinject() needs a fix too ;)
> > 
> > I agree. That one looks uglier though, I guess we'll have to
> > iterate through all hooks to note the previous one.
> 
> How about this? Unfortunately I don't think we can avoid
> iterating through all hooks without violating RCU rules.
> 
> 

       /* Continue traversal iff userspace said ok... */
        if (verdict == NF_REPEAT) {
-               elem = elem->prev;
-               verdict = NF_ACCEPT;
+               prev = NULL;
+               list_for_each_entry_rcu(i,
&nf_hooks[entry->pf][entry->hook],
+                                       list) {
+                       if (&i->list == elem)
+                               break;
+                       prev = i;

	
Hmm... what happens if "elem" was the first elem in list ?

We exit with prev = NULL  --> NF_DROP ?

I must miss something...

+               }
+
+               if (prev == NULL ||
+                   &i->list == &nf_hooks[entry->pf][entry->hook])
+                       verdict = NF_DROP;
+               else {
+                       elem = &prev->list;
+                       verdict = NF_ACCEPT;
+               }
        }



--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html