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] [thread-next>] [day] [month] [year] [list]
Date:	Wed, 28 Sep 2011 14:09:09 +0200
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Jason Wang <jasowang@...hat.com>
Cc:	netdev@...r.kernel.org, "David S. Miller" <davem@...hat.com>,
	linux-kernel@...r.kernel.org, Greg KH <gregkh@...e.de>,
	stable@...nel.org, "Michael S. Tsirkin" <mst@...hat.com>,
	Amos Kong <akong@...hat.com>
Subject: Re: Possible NULL dereference caused by -stable commit
 ef81bb40bf15f350fe865f31fa42f1082772a576

Le mercredi 28 septembre 2011 à 18:51 +0800, Jason Wang a écrit :
> Hi all:
> 
> A possible NULL dereference were noticed by the stable commit 
> ef81bb40bf15f350fe865f31fa42f1082772a576 (which is a backport of 
> 87c48fa3b4630905f98268dde838ee43626a060c). The case happens when bridge 
> froward a packet from guest to a physical nic, at this time no route is 
> attached to the skb which may lead a NULL dereference in 
> ipv6_select_ident(). -Next version have this check so it is fine. The 
> following patch may be used to avoid this but may also lead the ip 
> identification predicable, and this defect is also exist -next version 
> when no route because we still depends on a global variable to generate 
> the identification.  Any thought on this?

1) Discussion on current kernel :

All we need here is not the route but inet_peer, so that inet_getid()
can be called on it.

If no route is given to ipv6_select_ident(), at least we can try to get
inet_peer, and release it before exiting from ipv6_select_ident()

2) On stable kernel, we already use an array
(ipv6_fragmentation_id[FID_HASH_SZ];) to make less predictables
fragments ids.

So we could get dst addr from the packet to be forwarded instead of the
(possibly NULL) route.



--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Powered by blists - more mailing lists

Powered by Openwall GNU/*/Linux Powered by OpenVZ