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sctp: call rcu_read_lock before checking for duplicate transport nodes

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Commit cd2b708750 ("sctp: check duplicate node before inserting a
new transport") called rhltable_lookup() to check for the duplicate
transport node in transport rhashtable.

But rhltable_lookup() doesn't call rcu_read_lock inside, it could cause
a use-after-free issue if it tries to dereference the node that another
cpu has freed it. Note that sock lock can not avoid this as it is per
sock.

This patch is to fix it by calling rcu_read_lock before checking for
duplicate transport nodes.

Fixes: cd2b708750 ("sctp: check duplicate node before inserting a new transport")
Reported-by: Andrey Konovalov <andreyknvl@google.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Xin Long 2017-02-28 12:41:29 +08:00 committed by David S. Miller
parent 540b1c48c3
commit 5179b26694
1 changed files with 3 additions and 0 deletions
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3
net/sctp/input.c
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@ -884,14 +884,17 @@ int sctp_hash_transport(struct sctp_transport *t)
arg.paddr = &t->ipaddr;
arg.lport = htons(t->asoc->base.bind_addr.port);
rcu_read_lock();
list = rhltable_lookup(&sctp_transport_hashtable, &arg,
sctp_hash_params);
rhl_for_each_entry_rcu(transport, tmp, list, node)
if (transport->asoc->ep == t->asoc->ep) {
rcu_read_unlock();
err = -EEXIST;
goto out;
}
rcu_read_unlock();
err = rhltable_insert_key(&sctp_transport_hashtable, &arg,
&t->node, sctp_hash_params);