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author | Xin Long <lucien.xin@gmail.com> | 2016-09-10 23:11:23 +0800 |
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committer | David S. Miller <davem@davemloft.net> | 2016-09-13 11:44:58 -0400 |
commit | 715f5552b1e90ba3eecf6d1a6d044d0d5226663f (patch) | |
tree | 664441229dc29ce34920579093b0fcac85282626 /net | |
parent | 3e1be7ad2d38c6bd6aeef96df9bd0a7822f4e51c (diff) | |
download | op-kernel-dev-715f5552b1e90ba3eecf6d1a6d044d0d5226663f.zip op-kernel-dev-715f5552b1e90ba3eecf6d1a6d044d0d5226663f.tar.gz |
sctp: hold the transport before using it in sctp_hash_cmp
Since commit 4f0087812648 ("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: 4f0087812648 ("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>
Diffstat (limited to 'net')
-rw-r--r-- | net/sctp/input.c | 27 |
1 files changed, 17 insertions, 10 deletions
diff --git a/net/sctp/input.c b/net/sctp/input.c index 69444d3..1555fb8 100644 --- a/net/sctp/input.c +++ b/net/sctp/input.c @@ -796,27 +796,34 @@ struct sctp_hash_cmp_arg { static inline int sctp_hash_cmp(struct rhashtable_compare_arg *arg, const void *ptr) { + struct sctp_transport *t = (struct sctp_transport *)ptr; const struct sctp_hash_cmp_arg *x = arg->key; - const struct sctp_transport *t = ptr; - struct sctp_association *asoc = t->asoc; - const struct net *net = x->net; + struct sctp_association *asoc; + int err = 1; if (!sctp_cmp_addr_exact(&t->ipaddr, x->paddr)) - return 1; - if (!net_eq(sock_net(asoc->base.sk), net)) - return 1; + return err; + if (!sctp_transport_hold(t)) + return err; + + asoc = t->asoc; + if (!net_eq(sock_net(asoc->base.sk), x->net)) + goto out; if (x->ep) { if (x->ep != asoc->ep) - return 1; + goto out; } else { if (x->laddr->v4.sin_port != htons(asoc->base.bind_addr.port)) - return 1; + goto out; if (!sctp_bind_addr_match(&asoc->base.bind_addr, x->laddr, sctp_sk(asoc->base.sk))) - return 1; + goto out; } - return 0; + err = 0; +out: + sctp_transport_put(t); + return err; } static inline u32 sctp_hash_obj(const void *data, u32 len, u32 seed) |