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]
Date:   Mon, 13 Mar 2017 12:54:01 -0700 (PDT)
From:   David Miller <>
Subject: Re: [PATCH nf] ipv6: avoid write to a possibly cloned skb

From: Florian Westphal <>
Date: Mon, 13 Mar 2017 16:24:28 +0100

> ip6_fragment, in case skb has a fraglist, checks if the
> skb is cloned.  If it is, it will move to the 'slow path' and allocates
> new skbs for each fragment.
> However, right before entering the slowpath loop, it updates the
> nexthdr value of the last ipv6 extension header to NEXTHDR_FRAGMENT,
> to account for the fragment header that will be inserted in the new
> ipv6-fragment skbs.
> In case original skb is cloned this munges nexthdr value of another
> skb.  Avoid this by doing the nexthdr update for each of the new fragment
> skbs separately.
> This was observed with tcpdump on a bridge device where netfilter ipv6
> reassembly is active:  tcpdump shows malformed fragment headers as
> the l4 header (icmpv6, tcp, etc). is decoded as a fragment header.
> Cc: Hannes Frederic Sowa <>
> Reported-by: Andreas Karis <>
> Signed-off-by: Florian Westphal <>

Great catch Florian, applied, thanks.

Powered by blists - more mailing lists