net, bridge: convert net_bridge_vlan.refcnt 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>

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index c18682f804a0b4b40b76ceeae1998f21098c12c9..fd9ee73e0a6d6bfb0f1de47811e74012071d5196 100644 (file)
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -21,6 +21,7 @@
 #include <net/ip6_fib.h>
 #include <linux/if_vlan.h>
 #include <linux/rhashtable.h>
+#include <linux/refcount.h>
 
 #define BR_HASH_BITS 8
 #define BR_HASH_SIZE (1 << BR_HASH_BITS)
@@ -127,7 +128,7 @@ struct net_bridge_vlan {
                struct net_bridge_port  *port;
        };
        union {
-               atomic_t                refcnt;
+               refcount_t              refcnt;
                struct net_bridge_vlan  *brvlan;
        };
 

diff --git a/net/bridge/br_vlan.c b/net/bridge/br_vlan.c
index 26a1a56639b26f07ca40e661f74be4890f6e4b7a..233a30040c91fc8e9d26a320bd0696cb64571872 100644 (file)
--- a/net/bridge/br_vlan.c
+++ b/net/bridge/br_vlan.c
@@ -158,7 +158,7 @@ static struct net_bridge_vlan *br_vlan_get_master(struct net_bridge *br, u16 vid
                if (WARN_ON(!masterv))
                        return NULL;
        }
-       atomic_inc(&masterv->refcnt);
+       refcount_inc(&masterv->refcnt);
 
        return masterv;
 }
@@ -182,7 +182,7 @@ static void br_vlan_put_master(struct net_bridge_vlan *masterv)
                return;
 
        vg = br_vlan_group(masterv->br);
-       if (atomic_dec_and_test(&masterv->refcnt)) {
+       if (refcount_dec_and_test(&masterv->refcnt)) {
                rhashtable_remove_fast(&vg->vlan_hash,
                                       &masterv->vnode, br_vlan_rht_params);
                __vlan_del_list(masterv);
@@ -573,7 +573,7 @@ int br_vlan_add(struct net_bridge *br, u16 vid, u16 flags)
                                br_err(br, "failed insert local address into bridge forwarding table\n");
                                return ret;
                        }
-                       atomic_inc(&vlan->refcnt);
+                       refcount_inc(&vlan->refcnt);
                        vlan->flags |= BRIDGE_VLAN_INFO_BRENTRY;
                        vg->num_vlans++;
                }
@@ -595,7 +595,7 @@ int br_vlan_add(struct net_bridge *br, u16 vid, u16 flags)
        vlan->flags &= ~BRIDGE_VLAN_INFO_PVID;
        vlan->br = br;
        if (flags & BRIDGE_VLAN_INFO_BRENTRY)
-               atomic_set(&vlan->refcnt, 1);
+               refcount_set(&vlan->refcnt, 1);
        ret = __vlan_add(vlan, flags);
        if (ret) {
                free_percpu(vlan->stats);