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| author | Jon Paul Maloy <jon.maloy@ericsson.com> | 2016-02-24 11:00:19 -0500 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2016-02-25 17:04:48 -0500 |
| commit | b170997acedc6c11ed2ec07b8d415601e65bb452 (patch) | |
| tree | b0759cbe4ceec6d799d8830fd03f3fd5e357a271 /net/tipc/node.c | |
| parent | 3da7611f4285e0434dff62bcabb8b5bfdae5915f (diff) | |
| download | linux-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/node.c')
| -rw-r--r-- | net/tipc/node.c | 18 |
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) |