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authorJon Paul Maloy <jon.maloy@ericsson.com>2016-02-24 11:00:19 -0500
committerDavid S. Miller <davem@davemloft.net>2016-02-25 17:04:48 -0500
commitb170997acedc6c11ed2ec07b8d415601e65bb452 (patch)
treeb0759cbe4ceec6d799d8830fd03f3fd5e357a271 /net/tipc
parent3da7611f4285e0434dff62bcabb8b5bfdae5915f (diff)
downloadlinux-b170997acedc6c11ed2ec07b8d415601e65bb452.tar.bz2
tipc: eliminate risk of finding to-be-deleted node instance
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>
Diffstat (limited to 'net/tipc')
-rw-r--r--net/tipc/node.c18
1 files changed, 9 insertions, 9 deletions
diff --git a/net/tipc/node.c b/net/tipc/node.c
index 9fcc2fb0ee00..792bbcbb3eed 100644
--- a/net/tipc/node.c
+++ b/net/tipc/node.c
@@ -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)