net: sctp: sctp_sf_do_prm_asoc: do SCTP_CMD_INIT_CHOOSE_TRANSPORT first

While this currently cannot trigger any NULL pointer dereference in
sctp_seq_dump_local_addrs(), better change the order of commands to
prevent a future bug to happen. Although we first add SCTP_CMD_NEW_ASOC
and then set the SCTP_CMD_INIT_CHOOSE_TRANSPORT, it is okay for now,
since this primitive is only called by sctp_connect() or sctp_sendmsg()
with sctp_assoc_add_peer() set first. However, lets do this precaution
and first set the transport and then add it to the association hashlist
to prevent in future something to possibly triggering this.

Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/sctp/sm_statefuns.c b/net/sctp/sm_statefuns.c
index de1a0138317f482c028ce583c335501b14d9f917..b3d186856513235d7f3f8fdd580e6ffaa6275127 100644 (file)
--- a/net/sctp/sm_statefuns.c
+++ b/net/sctp/sm_statefuns.c
@@ -4632,16 +4632,16 @@ sctp_disposition_t sctp_sf_do_prm_asoc(struct net *net,
        if (!repl)
                goto nomem;
 
+       /* Choose transport for INIT. */
+       sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT,
+                       SCTP_CHUNK(repl));
+
        /* Cast away the const modifier, as we want to just
         * rerun it through as a sideffect.
         */
        my_asoc = (struct sctp_association *)asoc;
        sctp_add_cmd_sf(commands, SCTP_CMD_NEW_ASOC, SCTP_ASOC(my_asoc));
 
-       /* Choose transport for INIT. */
-       sctp_add_cmd_sf(commands, SCTP_CMD_INIT_CHOOSE_TRANSPORT,
-                       SCTP_CHUNK(repl));
-
        /* After sending the INIT, "A" starts the T1-init timer and
         * enters the COOKIE-WAIT state.
         */