caif: fix two caif_connect() bugs
caif_connect() might dereference a netdevice after dev_put() it.
It also doesnt check dev_get_by_index() return value and could
dereference a NULL pointer.
Fix it, using RCU to avoid taking a reference.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
CC: Sjur Braendeland <sjur.brandeland@stericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/caif/caif_socket.c b/net/caif/caif_socket.c
index 8ce9047..4bf28f2 100644
--- a/net/caif/caif_socket.c
+++ b/net/caif/caif_socket.c
@@ -827,6 +827,7 @@
long timeo;
int err;
int ifindex, headroom, tailroom;
+ unsigned int mtu;
struct net_device *dev;
lock_sock(sk);
@@ -896,15 +897,23 @@
cf_sk->sk.sk_state = CAIF_DISCONNECTED;
goto out;
}
- dev = dev_get_by_index(sock_net(sk), ifindex);
+
+ err = -ENODEV;
+ rcu_read_lock();
+ dev = dev_get_by_index_rcu(sock_net(sk), ifindex);
+ if (!dev) {
+ rcu_read_unlock();
+ goto out;
+ }
cf_sk->headroom = LL_RESERVED_SPACE_EXTRA(dev, headroom);
+ mtu = dev->mtu;
+ rcu_read_unlock();
+
cf_sk->tailroom = tailroom;
- cf_sk->maxframe = dev->mtu - (headroom + tailroom);
- dev_put(dev);
+ cf_sk->maxframe = mtu - (headroom + tailroom);
if (cf_sk->maxframe < 1) {
- pr_warning("CAIF: %s(): CAIF Interface MTU too small (%d)\n",
- __func__, dev->mtu);
- err = -ENODEV;
+ pr_warning("CAIF: %s(): CAIF Interface MTU too small (%u)\n",
+ __func__, mtu);
goto out;
}