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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>
zero-colors
Reshetova, Elena 2017-06-30 13:07:57 +03:00 committed by David S. Miller
parent 6343944bc1
commit 53869cebce
3 changed files with 6 additions and 6 deletions
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6
include/linux/skbuff.h
View File

@ -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)

2
include/net/netfilter/br_netfilter.h
View File

@ -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;
}

4
net/bridge/br_netfilter_hooks.c
View File

@ -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;