[PATCH net 1/2] sctp: fix invalid reference to the index variable of the iterator

[Xin Long]

Now in sctp_apply_peer_addr_params(), if SPP_IPV6_FLOWLABEL flag is set
and trans is NULL, it would use trans as the index variable to traverse
transport_addr_list, then trans is set as the last transport of it.

Later, if SPP_DSCP flag is set, it would enter into the wrong branch as
trans is actually an invalid reference.

So fix it by using a new index variable to traverse transport_addr_list
for both SPP_DSCP and SPP_IPV6_FLOWLABEL flags process.

Fixes: 0b0dce7a36fb ("sctp: add spp_ipv6_flowlabel and spp_dscp for 
sctp_paddrparams")
Reported-by: Julia Lawall <julia.law...@lip6.fr>
Signed-off-by: Xin Long <lucien....@gmail.com>
---
 net/sctp/socket.c | 24 +++++++++++++-----------
 1 file changed, 13 insertions(+), 11 deletions(-)

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index aa76586..a0ccfa4 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -2663,14 +2663,15 @@ static int sctp_apply_peer_addr_params(struct 
sctp_paddrparams *params,
                                           SCTP_FLOWLABEL_VAL_MASK;
                        trans->flowlabel |= SCTP_FLOWLABEL_SET_MASK;
                } else if (asoc) {
-                       list_for_each_entry(trans,
-                                           &asoc->peer.transport_addr_list,
+                       struct sctp_transport *t;
+
+                       list_for_each_entry(t, &asoc->peer.transport_addr_list,
                                            transports) {
-                               if (trans->ipaddr.sa.sa_family != AF_INET6)
+                               if (t->ipaddr.sa.sa_family != AF_INET6)
                                        continue;
-                               trans->flowlabel = params->spp_ipv6_flowlabel &
-                                                  SCTP_FLOWLABEL_VAL_MASK;
-                               trans->flowlabel |= SCTP_FLOWLABEL_SET_MASK;
+                               t->flowlabel = params->spp_ipv6_flowlabel &
+                                              SCTP_FLOWLABEL_VAL_MASK;
+                               t->flowlabel |= SCTP_FLOWLABEL_SET_MASK;
                        }
                        asoc->flowlabel = params->spp_ipv6_flowlabel &
                                          SCTP_FLOWLABEL_VAL_MASK;
@@ -2687,12 +2688,13 @@ static int sctp_apply_peer_addr_params(struct 
sctp_paddrparams *params,
                        trans->dscp = params->spp_dscp & SCTP_DSCP_VAL_MASK;
                        trans->dscp |= SCTP_DSCP_SET_MASK;
                } else if (asoc) {
-                       list_for_each_entry(trans,
-                                           &asoc->peer.transport_addr_list,
+                       struct sctp_transport *t;
+
+                       list_for_each_entry(t, &asoc->peer.transport_addr_list,
                                            transports) {
-                               trans->dscp = params->spp_dscp &
-                                             SCTP_DSCP_VAL_MASK;
-                               trans->dscp |= SCTP_DSCP_SET_MASK;
+                               t->dscp = params->spp_dscp &
+                                         SCTP_DSCP_VAL_MASK;
+                               t->dscp |= SCTP_DSCP_SET_MASK;
                        }
                        asoc->dscp = params->spp_dscp & SCTP_DSCP_VAL_MASK;
                        asoc->dscp |= SCTP_DSCP_SET_MASK;
-- 
2.1.0