net: convert nf_bridge_info.use from atomic_t to refcount_t

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@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: David S. Miller <davem@davemloft.net>

3 files changed, 6 insertions, 6 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index a17e235639ae..005793e01bd2 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -252,7 +252,7 @@ struct nf_conntrack {
 
 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
 struct nf_bridge_info {
-        atomic_t                use;
+        refcount_t              use;
         enum {
                 BRNF_PROTO_UNCHANGED,
                 BRNF_PROTO_8021Q,
@@ -3589,13 +3589,13 @@ static inline void nf_conntrack_get(struct nf_conntrack *nfct)
 #if IS_ENABLED(CONFIG_BRIDGE_NETFILTER)
 static inline void nf_bridge_put(struct nf_bridge_info *nf_bridge)
 {
-        if (nf_bridge && atomic_dec_and_test(&nf_bridge->use))
+        if (nf_bridge && refcount_dec_and_test(&nf_bridge->use))
                 kfree(nf_bridge);
 }
 static inline void nf_bridge_get(struct nf_bridge_info *nf_bridge)
 {
         if (nf_bridge)
-                atomic_inc(&nf_bridge->use);
+                refcount_inc(&nf_bridge->use);
 }
 #endif /* CONFIG_BRIDGE_NETFILTER */
 static inline void nf_reset(struct sk_buff *skb)
diff --git a/include/net/netfilter/br_netfilter.h b/include/net/netfilter/br_netfilter.h
index 0b0c35c37125..925524ede6c8 100644
--- a/include/net/netfilter/br_netfilter.h
+++ b/include/net/netfilter/br_netfilter.h
@@ -8,7 +8,7 @@ static inline struct nf_bridge_info *nf_bridge_alloc(struct sk_buff *skb)
         skb->nf_bridge = kzalloc(sizeof(struct nf_bridge_info), GFP_ATOMIC);
 
         if (likely(skb->nf_bridge))
-                atomic_set(&(skb->nf_bridge->use), 1);
+                refcount_set(&(skb->nf_bridge->use), 1);
 
         return skb->nf_bridge;
 }
diff --git a/net/bridge/br_netfilter_hooks.c b/net/bridge/br_netfilter_hooks.c
index 067cf0313449..2261e5194c82 100644
--- a/net/bridge/br_netfilter_hooks.c
+++ b/net/bridge/br_netfilter_hooks.c
@@ -149,12 +149,12 @@ static inline struct nf_bridge_info *nf_bridge_unshare(struct sk_buff *skb)
 {
         struct nf_bridge_info *nf_bridge = skb->nf_bridge;
 
-        if (atomic_read(&nf_bridge->use) > 1) {
+        if (refcount_read(&nf_bridge->use) > 1) {
                 struct nf_bridge_info *tmp = nf_bridge_alloc(skb);
 
                 if (tmp) {
                         memcpy(tmp, nf_bridge, sizeof(struct nf_bridge_info));
-                        atomic_set(&tmp->use, 1);
+                        refcount_set(&tmp->use, 1);
                 }
                 nf_bridge_put(nf_bridge);
                 nf_bridge = tmp;