[PATCH 6.8 015/158] netfilter: nf_tables: Fix potential data-race in __nft_obj_type_get()

Greg Kroah-Hartman
2024-04-23T21:40:56Z

From: Ziyang Xuan <william.xuanziyang@huawei.com>

[ Upstream commit d78d867dcea69c328db30df665be5be7d0148484 ]

nft_unregister_obj() can concurrent with __nft_obj_type_get(),
and there is not any protection when iterate over nf_tables_objects
list in __nft_obj_type_get(). Therefore, there is potential data-race
of nf_tables_objects list entry.

Use list_for_each_entry_rcu() to iterate over nf_tables_objects
list in __nft_obj_type_get(), and use rcu_read_lock() in the caller
nft_obj_type_get() to protect the entire type query process.

Fixes: e50092404c1b ("netfilter: nf_tables: add stateful objects")
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/netfilter/nf_tables_api.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/net/netfilter/nf_tables_api.c b/net/netfilter/nf_tables_api.c
index a1cf875e5d35f..ad9fb019684b3 100644
--- a/net/netfilter/nf_tables_api.c
+++ b/net/netfilter/nf_tables_api.c
@@ -7607,7 +7607,7 @@ static const struct nft_object_type *__nft_obj_type_get(u32 objtype, u8 family)
{
const struct nft_object_type *type;

- list_for_each_entry(type, &nf_tables_objects, list) {
+ list_for_each_entry_rcu(type, &nf_tables_objects, list) {
if (type->family != NFPROTO_UNSPEC &&
type->family != family)
continue;
@@ -7623,9 +7623,13 @@ nft_obj_type_get(struct net *net, u32 objtype, u8 family)
{
const struct nft_object_type *type;

+ rcu_read_lock();
type = __nft_obj_type_get(objtype, family);
- if (type != NULL && try_module_get(type->owner))
+ if (type != NULL && try_module_get(type->owner)) {
+ rcu_read_unlock();
return type;
+ }
+ rcu_read_unlock();

lockdep_nfnl_nft_mutex_not_held();
#ifdef CONFIG_MODULES
--
2.43.0