[SCTP]: Add RCU synchronization around sctp_localaddr_list
sctp_localaddr_list is modified dynamically via NETDEV_UP
and NETDEV_DOWN events, but there is not synchronization
between writer (even handler) and readers. As a result,
the readers can access an entry that has been freed and
crash the sytem.
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Sridhar Samdurala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index f8aa23d..e12fa0a 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -77,13 +77,18 @@
#include <asm/uaccess.h>
-/* Event handler for inet6 address addition/deletion events. */
+/* Event handler for inet6 address addition/deletion events.
+ * The sctp_local_addr_list needs to be protocted by a spin lock since
+ * multiple notifiers (say IPv4 and IPv6) may be running at the same
+ * time and thus corrupt the list.
+ * The reader side is protected with RCU.
+ */
static int sctp_inet6addr_event(struct notifier_block *this, unsigned long ev,
void *ptr)
{
struct inet6_ifaddr *ifa = (struct inet6_ifaddr *)ptr;
- struct sctp_sockaddr_entry *addr;
- struct list_head *pos, *temp;
+ struct sctp_sockaddr_entry *addr = NULL;
+ struct sctp_sockaddr_entry *temp;
switch (ev) {
case NETDEV_UP:
@@ -94,19 +99,26 @@
memcpy(&addr->a.v6.sin6_addr, &ifa->addr,
sizeof(struct in6_addr));
addr->a.v6.sin6_scope_id = ifa->idev->dev->ifindex;
- list_add_tail(&addr->list, &sctp_local_addr_list);
+ addr->valid = 1;
+ spin_lock_bh(&sctp_local_addr_lock);
+ list_add_tail_rcu(&addr->list, &sctp_local_addr_list);
+ spin_unlock_bh(&sctp_local_addr_lock);
}
break;
case NETDEV_DOWN:
- list_for_each_safe(pos, temp, &sctp_local_addr_list) {
- addr = list_entry(pos, struct sctp_sockaddr_entry, list);
- if (ipv6_addr_equal(&addr->a.v6.sin6_addr, &ifa->addr)) {
- list_del(pos);
- kfree(addr);
+ spin_lock_bh(&sctp_local_addr_lock);
+ list_for_each_entry_safe(addr, temp,
+ &sctp_local_addr_list, list) {
+ if (ipv6_addr_equal(&addr->a.v6.sin6_addr,
+ &ifa->addr)) {
+ addr->valid = 0;
+ list_del_rcu(&addr->list);
break;
}
}
-
+ spin_unlock_bh(&sctp_local_addr_lock);
+ if (addr && !addr->valid)
+ call_rcu(&addr->rcu, sctp_local_addr_free);
break;
}
@@ -367,7 +379,9 @@
addr->a.v6.sin6_port = 0;
addr->a.v6.sin6_addr = ifp->addr;
addr->a.v6.sin6_scope_id = dev->ifindex;
+ addr->valid = 1;
INIT_LIST_HEAD(&addr->list);
+ INIT_RCU_HEAD(&addr->rcu);
list_add_tail(&addr->list, addrlist);
}
}