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Xin Long authored
Since commit 4f008781 ("sctp: apply rhashtable api to send/recv path"), sctp uses transport rhashtable with .obj_cmpfn sctp_hash_cmp, in which it compares the members of the transport with the rhashtable args to check if it's the right transport. But sctp uses the transport without holding it in sctp_hash_cmp, it can cause a use-after-free panic. As after it gets transport from hashtable, another CPU may close the sk and free the asoc. In sctp_association_free, it frees all the transports, meanwhile, the assoc's refcnt may be reduced to 0, assoc can be destroyed by sctp_association_destroy. So after that, transport->assoc is actually an unavailable memory address in sctp_hash_cmp. Although sctp_hash_cmp is under rcu_read_lock, it still can not avoid this, as assoc is not freed by RCU. This patch is to hold the transport before checking it's members with sctp_transport_hold, in which it checks the refcnt first, holds it if it's not 0. Fixes: 4f008781 ("sctp: apply rhashtable api to send/recv path") Signed-off-by:
Xin Long <lucien.xin@gmail.com> Acked-by:
Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> Signed-off-by:
David S. Miller <davem@davemloft.net>
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