tipc: fix unsafe rcu locking when accessing publication list

The binding table's 'cluster_scope' list is rcu protected to handle
races between threads changing the list and those traversing the list at
the same moment. We have now found that the function named_distribute()
uses the regular list_for_each() macro to traverse the said list.
Likewise, the function tipc_named_withdraw() is removing items from the
same list using the regular list_del() call. When these two functions
execute in parallel we see occasional crashes.

This commit fixes this by adding the missing _rcu() suffixes.

Signed-off-by: Tung Nguyen <[email protected]>
Signed-off-by: Jon Maloy <[email protected]>
Signed-off-by: David S. Miller <[email protected]>

diff --git a/net/tipc/name_distr.c b/net/tipc/name_distr.c
index 51b4b96f89db3b2766fd81a22e092e58c8169c8a..3cfeb9df64b0008b894e7495cb0a00dd23938844 100644 (file)
--- a/net/tipc/name_distr.c
+++ b/net/tipc/name_distr.c
@@ -115,7 +115,7 @@ struct sk_buff *tipc_named_withdraw(struct net *net, struct publication *publ)
        struct sk_buff *buf;
        struct distr_item *item;
 
-       list_del(&publ->binding_node);
+       list_del_rcu(&publ->binding_node);
 
        if (publ->scope == TIPC_NODE_SCOPE)
                return NULL;
@@ -147,7 +147,7 @@ static void named_distribute(struct net *net, struct sk_buff_head *list,
                        ITEM_SIZE) * ITEM_SIZE;
        u32 msg_rem = msg_dsz;
 
-       list_for_each_entry(publ, pls, binding_node) {
+       list_for_each_entry_rcu(publ, pls, binding_node) {
                /* Prepare next buffer: */
                if (!skb) {
                        skb = named_prepare_buf(net, PUBLICATION, msg_rem,