ip: fix IP_CHECKSUM handling
authorPaolo Abeni <pabeni@redhat.com>
Tue, 21 Feb 2017 08:33:18 +0000 (09:33 +0100)
committerDavid S. Miller <davem@davemloft.net>
Tue, 21 Feb 2017 17:23:53 +0000 (12:23 -0500)
commitca4ef4574f1ee5252e2cd365f8f5d5bafd048f32
tree0e9ae821b92bfa2cb2e143e15b4b98e829d59528
parent8dcd81a993f4f65d22dfecb4360204b428c36cff
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>
net/ipv4/ip_sockglue.c