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netfilter: conntrack: nf_ct_gre_keymap_flush() removal

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nf_ct_gre_keymap_flush() is useless.
It is called from nf_conntrack_cleanup_net_list() only and tries to remove
nf_ct_gre_keymap entries from pernet gre keymap list. Though:
a) at this point the list should already be empty, all its entries were
deleted during the conntracks cleanup, because
nf_conntrack_cleanup_net_list() executes nf_ct_iterate_cleanup(kill_all)
before nf_conntrack_proto_pernet_fini():
 nf_conntrack_cleanup_net_list
  +- nf_ct_iterate_cleanup
  |   nf_ct_put
  |    nf_conntrack_put
  |     nf_conntrack_destroy
  |      destroy_conntrack
  |       destroy_gre_conntrack
  |        nf_ct_gre_keymap_destroy
  `- nf_conntrack_proto_pernet_fini
      nf_ct_gre_keymap_flush

b) Let's say we find that the keymap list is not empty. This means netns
still has a conntrack associated with gre, in which case we should not free
its memory, because this will lead to a double free and related crashes.
However I doubt it could have gone unnoticed for years, obviously
this does not happen in real life. So I think we can remove
both nf_ct_gre_keymap_flush() and nf_conntrack_proto_pernet_fini().

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
Acked-by: Florian Westphal <fw@strlen.de>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
This commit is contained in:
Vasily Averin 2021-07-01 08:02:24 +03:00 committed by Pablo Neira Ayuso
parent 4ca041f919
commit a23f89a999
4 changed files with 0 additions and 22 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

1
include/net/netfilter/nf_conntrack_core.h
View file

@ -30,7 +30,6 @@ void nf_conntrack_cleanup_net(struct net *net);
void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list);
void nf_conntrack_proto_pernet_init(struct net *net);
void nf_conntrack_proto_pernet_fini(struct net *net);
int nf_conntrack_proto_init(void);
void nf_conntrack_proto_fini(void);

1
net/netfilter/nf_conntrack_core.c
View file

@ -2457,7 +2457,6 @@ void nf_conntrack_cleanup_net_list(struct list_head *net_exit_list)
}
list_for_each_entry(net, net_exit_list, exit_list) {
nf_conntrack_proto_pernet_fini(net);
nf_conntrack_ecache_pernet_fini(net);
nf_conntrack_expect_pernet_fini(net);
free_percpu(net->ct.stat);

7
net/netfilter/nf_conntrack_proto.c
View file

@ -697,13 +697,6 @@ void nf_conntrack_proto_pernet_init(struct net *net)
#endif
}
void nf_conntrack_proto_pernet_fini(struct net *net)
{
#ifdef CONFIG_NF_CT_PROTO_GRE
nf_ct_gre_keymap_flush(net);
#endif
}
module_param_call(hashsize, nf_conntrack_set_hashsize, param_get_uint,
&nf_conntrack_htable_size, 0600);

13
net/netfilter/nf_conntrack_proto_gre.c
View file

@ -55,19 +55,6 @@ static inline struct nf_gre_net *gre_pernet(struct net *net)
return &net->ct.nf_ct_proto.gre;
}
void nf_ct_gre_keymap_flush(struct net *net)
{
struct nf_gre_net *net_gre = gre_pernet(net);
struct nf_ct_gre_keymap *km, *tmp;
spin_lock_bh(&keymap_lock);
list_for_each_entry_safe(km, tmp, &net_gre->keymap_list, list) {
list_del_rcu(&km->list);
kfree_rcu(km, rcu);
}
spin_unlock_bh(&keymap_lock);
}
static inline int gre_key_cmpfn(const struct nf_ct_gre_keymap *km,
const struct nf_conntrack_tuple *t)
{