The expectation helpers (expect_h245, expect_rtp_rtcp, expect_t120, and
expect_callforwarding) test whether NAT is required by comparing the
forward source IP against the reverse destination IP:

    memcmp(&ct->tuplehash[dir].tuple.src.u3,
           &ct->tuplehash[!dir].tuple.dst.u3,
           sizeof(ct->tuplehash[dir].tuple.src.u3))

This check is broken for multiple reasons:

1. It incorrectly evaluates to 0 in the reply direction
   (dir == IP_CT_DIR_REPLY) even under SNAT, because tuplehash[REPLY].src
   and tuplehash[ORIGINAL].dst both represent the remote peer's address.
2. In Destination NAT (DNAT) and hairpin setups, the sender's source IP
   is never modified, causing this check to evaluate to false even though
   NAT payload rewriting is necessary.

As a result, NAT payload mangling is bypassed, leaving internal addresses
untranslated inside the signaling packets and leading to call setup and
media stream failures.

Remove the redundant memcmp() checks across all four expectation helpers.
Verifying that nathook is present and that ct->status matches IPS_NAT_MASK
is sufficient to determine whether NAT handling should execute.

Fixes: f587de0e2feb ("[NETFILTER]: nf_conntrack/nf_nat: add H.323 helper port")
Cc: stable@vger.kernel.org
Signed-off-by: Subham Pal <subhampal789@gmail.com>
---
[Note: Raw patch attached to avoid webmail tab/whitespace corruption]