From: Eric Dumazet <eric.dumazet@gmail.com>
To: Mike Maloney <maloneykernel@gmail.com>,
netdev@vger.kernel.org, davem@davemloft.net
Cc: Mike Maloney <maloney@google.com>
Subject: Re: [PATCH net] ipv6: fix udpv6 sendmsg crash caused by too small MTU
Date: Wed, 10 Jan 2018 10:56:47 -0800 [thread overview]
Message-ID: <1515610607.131759.27.camel@gmail.com> (raw)
In-Reply-To: <20180110174510.138752-1-maloneykernel@gmail.com>
On Wed, 2018-01-10 at 12:45 -0500, Mike Maloney wrote:
> From: Mike Maloney <maloney@google.com>
>
> The logic in __ip6_append_data() assumes that the MTU is at least large
> enough for the headers. A device's MTU may be adjusted after being
> added while sendmsg() is processing data, resulting in
> __ip6_append_data() seeing any MTU. For an mtu smaller than the size of
> the fragmentation header, the math results in a negative 'maxfraglen',
> which causes problems when refragmenting any previous skb in the
> skb_write_queue, leaving it possibly malformed.
>
> Instead sendmsg returns EINVAL when the mtu is calculated to be less
> than IPV6_MIN_MTU.
>
> Reported-by: syzbot <syzkaller@googlegroups.com>
> Signed-off-by: Mike Maloney <maloney@google.com>
>
>
Reviewed-by: Eric Dumazet <edumazet@google.com>
next prev parent reply other threads:[~2018-01-10 18:56 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-10 17:45 [PATCH net] ipv6: fix udpv6 sendmsg crash caused by too small MTU Mike Maloney
2018-01-10 18:56 ` Eric Dumazet [this message]
2018-01-15 18:30 ` David Miller
-- strict thread matches above, loose matches on Subject: below --
2018-01-10 17:10 Mike Maloney
2018-01-10 17:21 ` Eric Dumazet
2018-01-10 17:43 ` Mike Maloney
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