Re: [PATCH v4] [net]: Fix skb->csum update in inet_proto_csum_replace16().

On Thu, Jan 23, 2020 at 12:33:28PM -0800, Praveen Chaudhary wrote:

skb->csum is updated incorrectly, when manipulation for NF_NAT_MANIP_SRC\DST
is done on IPV6 packet.

Fix:
There is no need to update skb->csum in inet_proto_csum_replace16(), because
update in two fields a.) IPv6 src/dst address and b.) L4 header checksum
cancels each other for skb->csum calculation.
Whereas inet_proto_csum_replace4 function needs to update skb->csum,
because update in 3 fields a.) IPv4 src/dst address, b.) IPv4 Header checksum
and c.) L4 header checksum results in same diff as L4 Header checksum for
skb->csum calculation.

Applied, thanks.