[PATCH 14/23] net, xfrm: convert xfrm_policy.refcnt from atomic_t to refcount_t

From: Elena Reshetova
Date: Fri Mar 17 2017 - 08:17:35 EST


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 <elena.reshetova@xxxxxxxxx>
Signed-off-by: Hans Liljestrand <ishkamiel@xxxxxxxxx>
Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
Signed-off-by: David Windsor <dwindsor@xxxxxxxxx>
---
include/net/xfrm.h | 6 +++---
net/key/af_key.c | 2 +-
net/xfrm/xfrm_policy.c | 4 ++--
3 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/include/net/xfrm.h b/include/net/xfrm.h
index 163cda5..be30846 100644
--- a/include/net/xfrm.h
+++ b/include/net/xfrm.h
@@ -525,7 +525,7 @@ struct xfrm_policy {

/* This lock only affects elements except for entry. */
rwlock_t lock;
- atomic_t refcnt;
+ refcount_t refcnt;
struct timer_list timer;

struct flow_cache_object flo;
@@ -781,14 +781,14 @@ static inline void xfrm_audit_state_icvfail(struct xfrm_state *x,
static inline void xfrm_pol_hold(struct xfrm_policy *policy)
{
if (likely(policy != NULL))
- atomic_inc(&policy->refcnt);
+ refcount_inc(&policy->refcnt);
}

void xfrm_policy_destroy(struct xfrm_policy *policy);

static inline void xfrm_pol_put(struct xfrm_policy *policy)
{
- if (atomic_dec_and_test(&policy->refcnt))
+ if (refcount_dec_and_test(&policy->refcnt))
xfrm_policy_destroy(policy);
}

diff --git a/net/key/af_key.c b/net/key/af_key.c
index c6252ed..d3611af 100644
--- a/net/key/af_key.c
+++ b/net/key/af_key.c
@@ -2152,7 +2152,7 @@ static int pfkey_xfrm_policy2msg(struct sk_buff *skb, const struct xfrm_policy *
}

hdr->sadb_msg_len = size / sizeof(uint64_t);
- hdr->sadb_msg_reserved = atomic_read(&xp->refcnt);
+ hdr->sadb_msg_reserved = refcount_read(&xp->refcnt);

return 0;
}
diff --git a/net/xfrm/xfrm_policy.c b/net/xfrm/xfrm_policy.c
index 236cbbc..91cf3e7 100644
--- a/net/xfrm/xfrm_policy.c
+++ b/net/xfrm/xfrm_policy.c
@@ -62,7 +62,7 @@ static struct xfrm_policy *__xfrm_policy_unlink(struct xfrm_policy *pol,

static inline bool xfrm_pol_hold_rcu(struct xfrm_policy *policy)
{
- return atomic_inc_not_zero(&policy->refcnt);
+ return refcount_inc_not_zero(&policy->refcnt);
}

static inline bool
@@ -292,7 +292,7 @@ struct xfrm_policy *xfrm_policy_alloc(struct net *net, gfp_t gfp)
INIT_HLIST_NODE(&policy->bydst);
INIT_HLIST_NODE(&policy->byidx);
rwlock_init(&policy->lock);
- atomic_set(&policy->refcnt, 1);
+ refcount_set(&policy->refcnt, 1);
skb_queue_head_init(&policy->polq.hold_queue);
setup_timer(&policy->timer, xfrm_policy_timer,
(unsigned long)policy);
--
2.7.4