ipv6: mcast: use rcu_assign_pointer() for __rcu list updates

Several places in net/ipv6/mcast.c update RCU-protected lists
(np->ipv6_mc_list, idev->mc_list, idev->mc_tomb) using direct pointer
assignments instead of rcu_assign_pointer():

1. In __ipv6_dev_mc_dec(), unlinking a group from idev->mc_list did:
       *map = ma->next;
   without rcu_assign_pointer() while concurrent readers traverse
   idev->mc_list locklessly under rcu_read_lock().
2. In ipv6_sock_mc_drop() and __ipv6_sock_mc_close(), unlinking a group
   from np->ipv6_mc_list directly assigned *lnk = mc_lst->next and
   np->ipv6_mc_list = mc_lst->next without rcu_assign_pointer(), racing
   with lockless readers in inet6_mc_check().
3. In __ipv6_sock_mc_join(), mc_lst->next was initialized to
   np->ipv6_mc_list via raw assignment before publishing mc_lst.
4. In mld_del_delrec() and __ipv6_dev_mc_inc(), __rcu source pointers
   passed into rcu_assign_pointer() lacked explicit dereference helpers.

Fix these by consistently using rcu_assign_pointer() along with
mc_dereference() / sock_dereference().

Fixes: 456b61bca8ee ("ipv6: mcast: RCU conversion")
Fixes: 88e2ca308094 ("mld: convert ifmcaddr6 to RCU")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Taehee Yoo <ap420073@gmail.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Link: https://patch.msgid.link/20260828084531.1826790-5-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

0 files changed, 0 insertions, 0 deletions