From 5179b26694c92373275e4933f5d0ff32d585c675 Mon Sep 17 00:00:00 2001 From: Xin Long Date: Tue, 28 Feb 2017 12:41:29 +0800 Subject: [PATCH] sctp: call rcu_read_lock before checking for duplicate transport nodes Commit cd2b70875058 ("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: cd2b70875058 ("sctp: check duplicate node before inserting a new transport") Reported-by: Andrey Konovalov Signed-off-by: Xin Long Acked-by: Neil Horman Signed-off-by: David S. Miller --- net/sctp/input.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/net/sctp/input.c b/net/sctp/input.c index fc458968fe4b..2a28ab20487f 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -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);