udplite: fix partial checksum initialization
authorAlexey Kodanev <alexey.kodanev@oracle.com>
Thu, 15 Feb 2018 17:18:43 +0000 (20:18 +0300)
committerDavid S. Miller <davem@davemloft.net>
Fri, 16 Feb 2018 20:57:42 +0000 (15:57 -0500)
commit15f35d49c93f4fa9875235e7bf3e3783d2dd7a1b
tree2d100c2307313118f62ae83634a3f23046fa1a90
parentda27988766e338e4a4fe198170497c0920395d4c
udplite: fix partial checksum initialization

Since UDP-Lite is always using checksum, the following path is
triggered when calculating pseudo header for it:

  udp4_csum_init() or udp6_csum_init()
    skb_checksum_init_zero_check()
      __skb_checksum_validate_complete()

The problem can appear if skb->len is less than CHECKSUM_BREAK. In
this particular case __skb_checksum_validate_complete() also invokes
__skb_checksum_complete(skb). If UDP-Lite is using partial checksum
that covers only part of a packet, the function will return bad
checksum and the packet will be dropped.

It can be fixed if we skip skb_checksum_init_zero_check() and only
set the required pseudo header checksum for UDP-Lite with partial
checksum before udp4_csum_init()/udp6_csum_init() functions return.

Fixes: ed70fcfcee95 ("net: Call skb_checksum_init in IPv4")
Fixes: e4f45b7f40bd ("net: Call skb_checksum_init in IPv6")
Signed-off-by: Alexey Kodanev <alexey.kodanev@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
include/net/udplite.h
net/ipv4/udp.c
net/ipv6/ip6_checksum.c