tree 76a6ad15a5555f0a3e383a88e00b6ca45b4d12b2
parent 7c56012e92b51030b13c4652a9494d422562d5d5
author Paolo Abeni <pabeni@redhat.com> 1487665998 +0100
committer Greg Kroah-Hartman <gregkh@linuxfoundation.org> 1488103851 +0100

ip: fix IP_CHECKSUM handling

[ Upstream commit ca4ef4574f1ee5252e2cd365f8f5d5bafd048f32 ]

The skbs processed by ip_cmsg_recv() are not guaranteed to
be linear e.g. when sending UDP packets over loopback with
MSGMORE.
Using csum_partial() on [potentially] the whole skb len
is dangerous; instead be on the safe side and use skb_checksum().

Thanks to syzkaller team to detect the issue and provide the
reproducer.

v1 -> v2:
 - move the variable declaration in a tighter scope

Fixes: ad6f939ab193 ("ip: Add offset parameter to ip_cmsg_recv")
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>