iv/linux
1
0
Fork 0
Code Issues Pull Requests Actions Packages Projects Releases Wiki Activity

tipc: eliminate risk of finding to-be-deleted node instance

Browse Source 
Although we have never seen it happen, we have identified the
following problematic scenario when nodes are stopped and deleted:

CPU0:                            CPU1:

tipc_node_xxx()                                   //ref == 1
   tipc_node_put()                                //ref -> 0
                                 tipc_node_find() // node still in table
       tipc_node_delete()
         list_del_rcu(n. list)
                                 tipc_node_get()  //ref -> 1, bad
         kfree_rcu()

                                 tipc_node_put() //ref to 0 again.
                                 kfree_rcu()     // BOOM!

We fix this by introducing use of the conditional kref_get_if_not_zero()
instead of kref_get() in the function tipc_node_find(). This eliminates
any risk of post-mortem access.

Reported-by: Zhijiang Hu <huzhijiang@gmail.com>
Acked-by: Ying Xue <ying.xue@windriver.com>
Signed-off-by: Jon Maloy <jon.maloy@ericsson.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Jon Paul Maloy 2016-02-24 11:00:19 -05:00 committed by David S. Miller
parent 3da7611f42
commit b170997ace
1 changed files with 9 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
net/tipc/node.c
View File

@ -245,23 +245,23 @@ static void tipc_node_get(struct tipc_node *node)
*/
static struct tipc_node *tipc_node_find(struct net *net, u32 addr)
{
struct tipc_net *tn = net_generic(net, tipc_net_id);
struct tipc_net *tn = tipc_net(net);
struct tipc_node *node;
unsigned int thash = tipc_hashfn(addr);
if (unlikely(!in_own_cluster_exact(net, addr)))
return NULL;
rcu_read_lock();
hlist_for_each_entry_rcu(node, &tn->node_htable[tipc_hashfn(addr)],
hash) {
if (node->addr == addr) {
tipc_node_get(node);
rcu_read_unlock();
return node;
}
hlist_for_each_entry_rcu(node, &tn->node_htable[thash], hash) {
if (node->addr != addr)
continue;
if (!kref_get_unless_zero(&node->kref))
node = NULL;
break;
}
rcu_read_unlock();
return NULL;
return node;
}
static void tipc_node_read_lock(struct tipc_node *n)