From: Wang Chen <redacted>
Date: Fri, 16 Nov 2007 10:46:26 +0800

The current kernel doesn't verify the udp checksum if user doesn't set a
socket filter.It's fine for LAN. But for WAN, it's not a good option.
Shall we fix it? Below is the patch to make udp checksum be always 
available.

[IPV4] UDP: Always checksum even if without socket filter
Make udp checksum be always available even if without socket filter.

Signed-off-by: Wang Chen <redacted>

It checks the checksum in udp_recvmsg() and udp_poll().

Please do not fix bugs via code inspection without writing
test programs to validate whether there is really a "bug"
here or not.