netfilter: refcounter conversions

refcount_t type and corresponding API (see include/linux/refcount.h)
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@intel.com>
Signed-off-by: Hans Liljestrand <ishkamiel@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: David Windsor <dwindsor@gmail.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

1 files changed, 9 insertions, 7 deletions

diff --git a/include/net/ip_vs.h b/include/net/ip_vs.h
index 7bdfa7d78363..8a4a57b887fb 100644
--- a/include/net/ip_vs.h
+++ b/include/net/ip_vs.h
@@ -12,6 +12,8 @@
 #include <linux/list.h>                 /* for struct list_head */
 #include <linux/spinlock.h>             /* for struct rwlock_t */
 #include <linux/atomic.h>               /* for struct atomic_t */
+#include <linux/refcount.h>             /* for struct refcount_t */
+
 #include <linux/compiler.h>
 #include <linux/timer.h>
 #include <linux/bug.h>
@@ -525,7 +527,7 @@ struct ip_vs_conn {
 	struct netns_ipvs	*ipvs;
 
 	/* counter and timer */
-	atomic_t		refcnt;		/* reference count */
+	refcount_t		refcnt;		/* reference count */
 	struct timer_list	timer;		/* Expiration timer */
 	volatile unsigned long	timeout;	/* timeout */
 
@@ -667,7 +669,7 @@ struct ip_vs_dest {
 	atomic_t		conn_flags;	/* flags to copy to conn */
 	atomic_t		weight;		/* server weight */
 
-	atomic_t		refcnt;		/* reference counter */
+	refcount_t		refcnt;		/* reference counter */
 	struct ip_vs_stats      stats;          /* statistics */
 	unsigned long		idle_start;	/* start time, jiffies */
 
@@ -1211,14 +1213,14 @@ struct ip_vs_conn * ip_vs_conn_out_get_proto(struct netns_ipvs *ipvs, int af,
  */
 static inline bool __ip_vs_conn_get(struct ip_vs_conn *cp)
 {
-	return atomic_inc_not_zero(&cp->refcnt);
+	return refcount_inc_not_zero(&cp->refcnt);
 }
 
 /* put back the conn without restarting its timer */
 static inline void __ip_vs_conn_put(struct ip_vs_conn *cp)
 {
 	smp_mb__before_atomic();
-	atomic_dec(&cp->refcnt);
+	refcount_dec(&cp->refcnt);
 }
 void ip_vs_conn_put(struct ip_vs_conn *cp);
 void ip_vs_conn_fill_cport(struct ip_vs_conn *cp, __be16 cport);
@@ -1410,18 +1412,18 @@ void ip_vs_try_bind_dest(struct ip_vs_conn *cp);
 
 static inline void ip_vs_dest_hold(struct ip_vs_dest *dest)
 {
-	atomic_inc(&dest->refcnt);
+	refcount_inc(&dest->refcnt);
 }
 
 static inline void ip_vs_dest_put(struct ip_vs_dest *dest)
 {
 	smp_mb__before_atomic();
-	atomic_dec(&dest->refcnt);
+	refcount_dec(&dest->refcnt);
 }
 
 static inline void ip_vs_dest_put_and_free(struct ip_vs_dest *dest)
 {
-	if (atomic_dec_and_test(&dest->refcnt))
+	if (refcount_dec_and_test(&dest->refcnt))
 		kfree(dest);
 }