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Merge branch 'mctp-incorrect-addr-refs'

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Matt Johnston says:

====================
mctp: Fix incorrect refs for extended addr

This fixes an incorrect netdev unref and also addresses the race
condition identified by Jakub in v2. Thanks for the review.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
David S. Miller
2022-02-23 12:29:15 +00:00
parent 4767b7e2ed e297db3ead
commit 3185485cfa
3 changed files with 24 additions and 11 deletions
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21
net/mctp/device.c
View File

@@ -25,12 +25,25 @@ struct mctp_dump_cb {
size_t a_idx;
};
/* unlocked: caller must hold rcu_read_lock */
/* unlocked: caller must hold rcu_read_lock.
* Returned mctp_dev has its refcount incremented, or NULL if unset.
*/
struct mctp_dev *__mctp_dev_get(const struct net_device *dev)
{
return rcu_dereference(dev->mctp_ptr);
struct mctp_dev *mdev = rcu_dereference(dev->mctp_ptr);
/* RCU guarantees that any mdev is still live.
* Zero refcount implies a pending free, return NULL.
*/
if (mdev)
if (!refcount_inc_not_zero(&mdev->refs))
return NULL;
return mdev;
}
/* Returned mctp_dev does not have refcount incremented. The returned pointer
* remains live while rtnl_lock is held, as that prevents mctp_unregister()
*/
struct mctp_dev *mctp_dev_get_rtnl(const struct net_device *dev)
{
return rtnl_dereference(dev->mctp_ptr);
@@ -124,6 +137,7 @@ static int mctp_dump_addrinfo(struct sk_buff *skb, struct netlink_callback *cb)
if (mdev) {
rc = mctp_dump_dev_addrinfo(mdev,
skb, cb);
mctp_dev_put(mdev);
// Error indicates full buffer, this
// callback will get retried.
if (rc < 0)
@@ -298,7 +312,7 @@ void mctp_dev_hold(struct mctp_dev *mdev)
void mctp_dev_put(struct mctp_dev *mdev)
{
if (refcount_dec_and_test(&mdev->refs)) {
if (mdev && refcount_dec_and_test(&mdev->refs)) {
dev_put(mdev->dev);
kfree_rcu(mdev, rcu);
}
@@ -370,6 +384,7 @@ static size_t mctp_get_link_af_size(const struct net_device *dev,
if (!mdev)
return 0;
ret = nla_total_size(4); /* IFLA_MCTP_NET */
mctp_dev_put(mdev);
return ret;
}

13
net/mctp/route.c
View File

@@ -836,9 +836,8 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
{
struct mctp_sock *msk = container_of(sk, struct mctp_sock, sk);
struct mctp_skb_cb *cb = mctp_cb(skb);
struct mctp_route tmp_rt;
struct mctp_route tmp_rt = {0};
struct mctp_sk_key *key;
struct net_device *dev;
struct mctp_hdr *hdr;
unsigned long flags;
unsigned int mtu;
@@ -851,12 +850,12 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
if (rt) {
ext_rt = false;
dev = NULL;
if (WARN_ON(!rt->dev))
goto out_release;
} else if (cb->ifindex) {
struct net_device *dev;
ext_rt = true;
rt = &tmp_rt;
@@ -866,7 +865,6 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
rcu_read_unlock();
return rc;
}
rt->dev = __mctp_dev_get(dev);
rcu_read_unlock();
@@ -947,10 +945,9 @@ int mctp_local_output(struct sock *sk, struct mctp_route *rt,
if (!ext_rt)
mctp_route_release(rt);
dev_put(dev);
mctp_dev_put(tmp_rt.dev);
return rc;
}
/* route management */
@@ -1124,11 +1121,13 @@ static int mctp_pkttype_receive(struct sk_buff *skb, struct net_device *dev,
rt->output(rt, skb);
mctp_route_release(rt);
mctp_dev_put(mdev);
return NET_RX_SUCCESS;
err_drop:
kfree_skb(skb);
mctp_dev_put(mdev);
return NET_RX_DROP;
}

1
net/mctp/test/utils.c
View File

@@ -54,7 +54,6 @@ struct mctp_test_dev *mctp_test_create_dev(void)
rcu_read_lock();
dev->mdev = __mctp_dev_get(ndev);
mctp_dev_hold(dev->mdev);
rcu_read_unlock();
return dev;