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/datagram.c b/net/core/datagram.c
index e5311a7..95d4354 100644
--- a/net/core/datagram.c
+++ b/net/core/datagram.c
@@ -188,7 +188,7 @@ struct sk_buff *__skb_try_recv_from_queue(struct sock *sk,
}
}
*peeked = 1;
- atomic_inc(&skb->users);
+ refcount_inc(&skb->users);
} else {
__skb_unlink(skb, queue);
if (destructor)
@@ -358,7 +358,7 @@ int __sk_queue_drop_skb(struct sock *sk, struct sk_buff_head *sk_queue,
spin_lock_bh(&sk_queue->lock);
if (skb == skb_peek(sk_queue)) {
__skb_unlink(skb, sk_queue);
- atomic_dec(&skb->users);
+ refcount_dec(&skb->users);
if (destructor)
destructor(sk, skb);
err = 0;
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
diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index 37c1e34..a835155 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -277,7 +277,7 @@ static void zap_completion_queue(void)
struct sk_buff *skb = clist;
clist = clist->next;
if (!skb_irq_freeable(skb)) {
- atomic_inc(&skb->users);
+ refcount_inc(&skb->users);
dev_kfree_skb_any(skb); /* put this one back */
} else {
__kfree_skb(skb);
@@ -309,7 +309,7 @@ static struct sk_buff *find_skb(struct netpoll *np, int len, int reserve)
return NULL;
}
- atomic_set(&skb->users, 1);
+ refcount_set(&skb->users, 1);
skb_reserve(skb, reserve);
return skb;
}
diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index 2dd42c5..6e1e10f 100644
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3363,7 +3363,7 @@ static void pktgen_wait_for_skb(struct pktgen_dev *pkt_dev)
{
ktime_t idle_start = ktime_get();
- while (atomic_read(&(pkt_dev->skb->users)) != 1) {
+ while (refcount_read(&(pkt_dev->skb->users)) != 1) {
if (signal_pending(current))
break;
@@ -3420,7 +3420,7 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
if (pkt_dev->xmit_mode == M_NETIF_RECEIVE) {
skb = pkt_dev->skb;
skb->protocol = eth_type_trans(skb, skb->dev);
- atomic_add(burst, &skb->users);
+ refcount_add(burst, &skb->users);
local_bh_disable();
do {
ret = netif_receive_skb(skb);
@@ -3428,11 +3428,11 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
pkt_dev->errors++;
pkt_dev->sofar++;
pkt_dev->seq_num++;
- if (atomic_read(&skb->users) != burst) {
+ if (refcount_read(&skb->users) != burst) {
/* skb was queued by rps/rfs or taps,
* so cannot reuse this skb
*/
- atomic_sub(burst - 1, &skb->users);
+ WARN_ON(refcount_sub_and_test(burst - 1, &skb->users));
/* get out of the loop and wait
* until skb is consumed
*/
@@ -3446,7 +3446,7 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
goto out; /* Skips xmit_mode M_START_XMIT */
} else if (pkt_dev->xmit_mode == M_QUEUE_XMIT) {
local_bh_disable();
- atomic_inc(&pkt_dev->skb->users);
+ refcount_inc(&pkt_dev->skb->users);
ret = dev_queue_xmit(pkt_dev->skb);
switch (ret) {
@@ -3487,7 +3487,7 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
pkt_dev->last_ok = 0;
goto unlock;
}
- atomic_add(burst, &pkt_dev->skb->users);
+ refcount_add(burst, &pkt_dev->skb->users);
xmit_more:
ret = netdev_start_xmit(pkt_dev->skb, odev, txq, --burst > 0);
@@ -3513,11 +3513,11 @@ static void pktgen_xmit(struct pktgen_dev *pkt_dev)
/* fallthru */
case NETDEV_TX_BUSY:
/* Retry it next time */
- atomic_dec(&(pkt_dev->skb->users));
+ refcount_dec(&(pkt_dev->skb->users));
pkt_dev->last_ok = 0;
}
if (unlikely(burst))
- atomic_sub(burst, &pkt_dev->skb->users);
+ WARN_ON(refcount_sub_and_test(burst, &pkt_dev->skb->users));
unlock:
HARD_TX_UNLOCK(odev, txq);
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index ed51de5..d1ba909 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -649,7 +649,7 @@ int rtnetlink_send(struct sk_buff *skb, struct net *net, u32 pid, unsigned int g
NETLINK_CB(skb).dst_group = group;
if (echo)
- atomic_inc(&skb->users);
+ refcount_inc(&skb->users);
netlink_broadcast(rtnl, skb, pid, group, GFP_KERNEL);
if (echo)
err = netlink_unicast(rtnl, skb, pid, MSG_DONTWAIT);
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index f75897a..45dc662 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -176,7 +176,7 @@ struct sk_buff *__alloc_skb_head(gfp_t gfp_mask, int node)
memset(skb, 0, offsetof(struct sk_buff, tail));
skb->head = NULL;
skb->truesize = sizeof(struct sk_buff);
- atomic_set(&skb->users, 1);
+ refcount_set(&skb->users, 1);
skb->mac_header = (typeof(skb->mac_header))~0U;
out:
@@ -247,7 +247,7 @@ struct sk_buff *__alloc_skb(unsigned int size, gfp_t gfp_mask,
/* Account for allocated memory : skb + skb->head */
skb->truesize = SKB_TRUESIZE(size);
skb->pfmemalloc = pfmemalloc;
- atomic_set(&skb->users, 1);
+ refcount_set(&skb->users, 1);
skb->head = data;
skb->data = data;
skb_reset_tail_pointer(skb);
@@ -314,7 +314,7 @@ struct sk_buff *__build_skb(void *data, unsigned int frag_size)
memset(skb, 0, offsetof(struct sk_buff, tail));
skb->truesize = SKB_TRUESIZE(size);
- atomic_set(&skb->users, 1);
+ refcount_set(&skb->users, 1);
skb->head = data;
skb->data = data;
skb_reset_tail_pointer(skb);
@@ -915,7 +915,7 @@ static struct sk_buff *__skb_clone(struct sk_buff *n, struct sk_buff *skb)
C(head_frag);
C(data);
C(truesize);
- atomic_set(&n->users, 1);
+ refcount_set(&n->users, 1);
atomic_inc(&(skb_shinfo(skb)->dataref));
skb->cloned = 1;