netfilter: nf_tables: Fix potential data-race in __nft_flowtable_type_get()

stable inclusion
from stable-v4.19.312
commit 69d1fe14a680042ec913f22196b58e2c8ff1b007
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/I9QG2A
CVE: CVE-2024-35898

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=69d1fe14a680042ec913f22196b58e2c8ff1b007



--------------------------------

commit 24225011d81b471acc0e1e315b7d9905459a6304 upstream.

nft_unregister_flowtable_type() within nf_flow_inet_module_exit() can
concurrent with __nft_flowtable_type_get() within nf_tables_newflowtable().
And thhere is not any protection when iterate over nf_tables_flowtables
list in __nft_flowtable_type_get(). Therefore, there is pertential
data-race of nf_tables_flowtables list entry.

Use list_for_each_entry_rcu() to iterate over nf_tables_flowtables list
in __nft_flowtable_type_get(), and use rcu_read_lock() in the caller
nft_flowtable_type_get() to protect the entire type query process.

Fixes: 3b49e2e9 ("netfilter: nf_tables: add flow table netlink frontend")
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ziyang Xuan <william.xuanziyang@huawei.com>