netdev - [Question] Dead code in rawv6_mh_filter

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20260131150212.3292929-1-ingyujang25@korea.ac.kr>
Date: Sun,  1 Feb 2026 00:02:12 +0900
From: Ingyu Jang <ingyujang25@...ea.ac.kr>
To: netdev@...r.kernel.org
Cc: davem@...emloft.net,
	dsahern@...nel.org,
	edumazet@...gle.com,
	Ingyu Jang <ingyujang25@...ea.ac.kr>
Subject: [Question] Dead code in rawv6_mh_filter_register()?

Hi,

I noticed that in net/ipv6/raw.c, the function
rawv6_mh_filter_register() always returns 0.

The function (at line 117) simply performs:
  - rcu_assign_pointer(mh_filter, filter)
  - return 0

However, in net/ipv6/mip6.c, the function mip6_init() checks the
return value and has error handling (at line 381):

  if (rawv6_mh_filter_register(mip6_mh_filter) < 0) {
      pr_info("%s: can't add rawv6 mh filter\n", __func__);
      goto mip6_rawv6_mh_fail;
  }

Since rawv6_mh_filter_register() never fails, this error path
appears to be dead code. The same applies to
rawv6_mh_filter_unregister() in mip6_fini().

Is this intentional defensive coding for potential future changes,
or could this be cleaned up by making these functions return void?

Thanks,
Ingyu Jang