refcount_t type and corresponding API should be used instead of atomic_t when the variable is used as a reference counter. This allows to avoid accidental refcounter overflows that might lead to use-after-free situations.
Signed-off-by: Elena Reshetova <[email protected]> Signed-off-by: Hans Liljestrand <[email protected]> Signed-off-by: Kees Cook <[email protected]> Signed-off-by: David Windsor <[email protected]> --- include/net/netfilter/nf_conntrack_expect.h | 4 +++- net/netfilter/nf_conntrack_expect.c | 10 +++++----- net/netfilter/nf_conntrack_netlink.c | 4 ++-- 3 files changed, 10 insertions(+), 8 deletions(-) diff --git a/include/net/netfilter/nf_conntrack_expect.h b/include/net/netfilter/nf_conntrack_expect.h index 5ed33ea..65cc2cb 100644 --- a/include/net/netfilter/nf_conntrack_expect.h +++ b/include/net/netfilter/nf_conntrack_expect.h @@ -5,6 +5,8 @@ #ifndef _NF_CONNTRACK_EXPECT_H #define _NF_CONNTRACK_EXPECT_H +#include <linux/refcount.h> + #include <net/netfilter/nf_conntrack.h> #include <net/netfilter/nf_conntrack_zones.h> @@ -37,7 +39,7 @@ struct nf_conntrack_expect { struct timer_list timeout; /* Usage count. */ - atomic_t use; + refcount_t use; /* Flags */ unsigned int flags; diff --git a/net/netfilter/nf_conntrack_expect.c b/net/netfilter/nf_conntrack_expect.c index 4b2e1fb..cb29e59 100644 --- a/net/netfilter/nf_conntrack_expect.c +++ b/net/netfilter/nf_conntrack_expect.c @@ -133,7 +133,7 @@ nf_ct_expect_find_get(struct net *net, rcu_read_lock(); i = __nf_ct_expect_find(net, zone, tuple); - if (i && !atomic_inc_not_zero(&i->use)) + if (i && !refcount_inc_not_zero(&i->use)) i = NULL; rcu_read_unlock(); @@ -186,7 +186,7 @@ nf_ct_find_expectation(struct net *net, return NULL; if (exp->flags & NF_CT_EXPECT_PERMANENT) { - atomic_inc(&exp->use); + refcount_inc(&exp->use); return exp; } else if (del_timer(&exp->timeout)) { nf_ct_unlink_expect(exp); @@ -275,7 +275,7 @@ struct nf_conntrack_expect *nf_ct_expect_alloc(struct nf_conn *me) return NULL; new->master = me; - atomic_set(&new->use, 1); + refcount_set(&new->use, 1); return new; } EXPORT_SYMBOL_GPL(nf_ct_expect_alloc); @@ -348,7 +348,7 @@ static void nf_ct_expect_free_rcu(struct rcu_head *head) void nf_ct_expect_put(struct nf_conntrack_expect *exp) { - if (atomic_dec_and_test(&exp->use)) + if (refcount_dec_and_test(&exp->use)) call_rcu(&exp->rcu, nf_ct_expect_free_rcu); } EXPORT_SYMBOL_GPL(nf_ct_expect_put); @@ -361,7 +361,7 @@ static void nf_ct_expect_insert(struct nf_conntrack_expect *exp) unsigned int h = nf_ct_expect_dst_hash(net, &exp->tuple); /* two references : one for hash insert, one for the timer */ - atomic_add(2, &exp->use); + refcount_add(2, &exp->use); hlist_add_head(&exp->lnode, &master_help->expectations); master_help->expecting[exp->class]++; diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c index 6806b5e..d49cc1e 100644 --- a/net/netfilter/nf_conntrack_netlink.c +++ b/net/netfilter/nf_conntrack_netlink.c @@ -2693,7 +2693,7 @@ ctnetlink_exp_dump_table(struct sk_buff *skb, struct netlink_callback *cb) cb->nlh->nlmsg_seq, IPCTNL_MSG_EXP_NEW, exp) < 0) { - if (!atomic_inc_not_zero(&exp->use)) + if (!refcount_inc_not_zero(&exp->use)) continue; cb->args[1] = (unsigned long)exp; goto out; @@ -2739,7 +2739,7 @@ ctnetlink_exp_ct_dump_table(struct sk_buff *skb, struct netlink_callback *cb) cb->nlh->nlmsg_seq, IPCTNL_MSG_EXP_NEW, exp) < 0) { - if (!atomic_inc_not_zero(&exp->use)) + if (!refcount_inc_not_zero(&exp->use)) continue; cb->args[1] = (unsigned long)exp; goto out; -- 2.7.4
