tree 0e9ae821b92bfa2cb2e143e15b4b98e829d59528
parent 8dcd81a993f4f65d22dfecb4360204b428c36cff
author Paolo Abeni <pabeni@redhat.com> 1487665998 +0100
committer David S. Miller <davem@davemloft.net> 1487697833 -0500

ip: fix IP_CHECKSUM handling

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>