[PATCH net-next v2 0/3] net: Avoid ehash lookup races

[xuanqiang.luo@linux.dev]

From: Xuanqiang Luo <luoxuanqiang@kylinos.cn>

After replacing R/W locks with RCU in commit 3ab5aee7fe84 ("net: Convert
TCP & DCCP hash tables to use RCU / hlist_nulls"), a race window emerged
during the switch from reqsk/sk to sk/tw.

Now that both timewait sock (tw) and full sock (sk) reside on the same
ehash chain, it is appropriate to introduce hlist_nulls replace
operations, to eliminate the race conditions caused by this window.

---
Changes:
  v2:
    * Patch 1
	* Use WRITE_ONCE() to initialize old->pprev. 
    * Patch 2&3
	* Optimize sk hashed check. Thanks Kuni for pointing it out!

  v1: https://lore.kernel.org/all/20250915070308.111816-1-xuanqiang.luo@linux.dev/

Xuanqiang Luo (3):
  rculist: Add __hlist_nulls_replace_rcu() and
    hlist_nulls_replace_init_rcu()
  inet: Avoid ehash lookup race in inet_ehash_insert()
  inet: Avoid ehash lookup race in inet_twsk_hashdance_schedule()

 include/linux/rculist_nulls.h | 61 +++++++++++++++++++++++++++++++++++
 include/net/sock.h            | 23 +++++++++++++
 net/ipv4/inet_hashtables.c    |  4 ++-
 net/ipv4/inet_timewait_sock.c | 15 ++++-----
 4 files changed, 93 insertions(+), 10 deletions(-)

-- 
2.25.1