net: convert sk_buff.users 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/core/dev.c b/net/core/dev.c
index 88927f1..b999489 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1862,7 +1862,7 @@ static inline int deliver_skb(struct sk_buff *skb,
{
if (unlikely(skb_orphan_frags(skb, GFP_ATOMIC)))
return -ENOMEM;
- atomic_inc(&skb->users);
+ refcount_inc(&skb->users);
return pt_prev->func(skb, skb->dev, pt_prev, orig_dev);
}
@@ -2484,10 +2484,10 @@ void __dev_kfree_skb_irq(struct sk_buff *skb, enum skb_free_reason reason)
if (unlikely(!skb))
return;
- if (likely(atomic_read(&skb->users) == 1)) {
+ if (likely(refcount_read(&skb->users) == 1)) {
smp_rmb();
- atomic_set(&skb->users, 0);
- } else if (likely(!atomic_dec_and_test(&skb->users))) {
+ refcount_set(&skb->users, 0);
+ } else if (likely(!refcount_dec_and_test(&skb->users))) {
return;
}
get_kfree_skb_cb(skb)->reason = reason;
@@ -3955,7 +3955,7 @@ static __latent_entropy void net_tx_action(struct softirq_action *h)
clist = clist->next;
- WARN_ON(atomic_read(&skb->users));
+ WARN_ON(refcount_read(&skb->users));
if (likely(get_kfree_skb_cb(skb)->reason == SKB_REASON_CONSUMED))
trace_consume_skb(skb);
else