netdev - Re: sending VLAN packets via packet

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, 06 Oct 2010 23:53:43 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	phil@....cc
Cc:	netdev@...r.kernel.org, johann.baudy@...-log.net,
	eric.dumazet@...il.com
Subject: Re: sending VLAN packets via packet_mmap

From: Phil Sutter <phil@....cc>
Date: Thu, 30 Sep 2010 21:24:14 +0200

> The actual problem in tpacket_snd() is this:
> 
> | reserve = dev->hard_header_len;
> | [...]
> | if (size_max > dev->mtu + reserve)
> | 	size_max = dev->mtu + reserve;
> 
> I guess the check is there to avoid skb overflows on malicious data
> input. Is this correct? Are there other reasons for it's existence?

We can add a special allowance of 4 extra bytes in this size check
_iff_ the device is ethernet and the NETIF_F_VLAN_CHALLENGED netdev
feature bit is not set.

--
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