[Devel] [PATCH VZ7 7/7] netfilter: ipset: Fix suspicious rcu_dereference_protected()

[Pavel Tikhomirov]

From: Jozsef Kadlecsik <kadlec at netfilter.org>

When destroying all sets, we are either in pernet exit phase or
are executing a "destroy all sets command" from userspace. The latter
was taken into account in ip_set_dereference() (nfnetlink mutex is held),
but the former was not. The patch adds the required check to
rcu_dereference_protected() in ip_set_dereference().

Fixes: 4e7aaa6b82d6 ("netfilter: ipset: Fix race between namespace cleanup and gc in the list:set type")
Reported-by: syzbot+b62c37cdd58103293a5a at syzkaller.appspotmail.com
Reported-by: syzbot+cfbe1da5fdfc39efc293 at syzkaller.appspotmail.com
Reported-by: kernel test robot <oliver.sang at intel.com>
Closes: https://lore.kernel.org/oe-lkp/202406141556.e0b6f17e-lkp@intel.com
Signed-off-by: Jozsef Kadlecsik <kadlec at netfilter.org>
Signed-off-by: Pablo Neira Ayuso <pablo at netfilter.org>

https://virtuozzo.atlassian.net/browse/PSBM-155867
(cherry picked from commit 8ecd06277a7664f4ef018abae3abd3451d64e7a6)
Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
---
 net/netfilter/ipset/ip_set_core.c | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/net/netfilter/ipset/ip_set_core.c b/net/netfilter/ipset/ip_set_core.c
index 61d4579617081..d7a4a42a20319 100644
--- a/net/netfilter/ipset/ip_set_core.c
+++ b/net/netfilter/ipset/ip_set_core.c
@@ -56,12 +56,13 @@ MODULE_DESCRIPTION("core IP set support");
 MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_IPSET);
 
 /* When the nfnl mutex or ip_set_ref_lock is held: */
-#define ip_set_dereference(p)		\
-	rcu_dereference_protected(p,	\
+#define ip_set_dereference(inst)	\
+	rcu_dereference_protected((inst)->ip_set_list,	\
 		lockdep_nfnl_is_held(NFNL_SUBSYS_IPSET) || \
-		lockdep_is_held(&ip_set_ref_lock))
+		lockdep_is_held(&ip_set_ref_lock) || \
+		(inst)->is_deleted)
 #define ip_set(inst, id)		\
-	ip_set_dereference((inst)->ip_set_list)[id]
+	ip_set_dereference(inst)[id]
 #define ip_set_ref_netlink(inst,id)	\
 	rcu_dereference_raw((inst)->ip_set_list)[id]
 #define ip_set_dereference_nfnl(p)	\
@@ -989,7 +990,7 @@ ip_set_create(struct sock *ctnl, struct sk_buff *skb,
 		if (!list)
 			goto cleanup;
 		/* nfnl mutex is held, both lists are valid */
-		tmp = ip_set_dereference(inst->ip_set_list);
+		tmp = ip_set_dereference(inst);
 		memcpy(list, tmp, sizeof(struct ip_set *) * inst->ip_set_max);
 		rcu_assign_pointer(inst->ip_set_list, list);
 		/* Make sure all current packets have passed through */
-- 
2.46.0