[SCTP]: Fix protocol violation when receiving an error lenght INIT-ACK

When receiving an error length INIT-ACK during COOKIE-WAIT,
a 0-vtag ABORT will be responsed. This action violates the
protocol apparently. This patch achieves the following things.
1 If the INIT-ACK contains all the fixed parameters, use init-tag
  recorded from INIT-ACK as vtag.
2 If the INIT-ACK doesn't contain all the fixed parameters,
  just reflect its vtag.

Signed-off-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/sctp/sm_sideeffect.c b/net/sctp/sm_sideeffect.c
index 28eb38eb6083..a4763fd24fd8 100644
--- a/net/sctp/sm_sideeffect.c
+++ b/net/sctp/sm_sideeffect.c
@@ -1536,6 +1536,9 @@ static int sctp_cmd_interpreter(sctp_event_t event_type,
                         error = sctp_auth_asoc_init_active_key(asoc,
                                                 GFP_ATOMIC);
                         break;
+                case SCTP_CMD_UPDATE_INITTAG:
+                        asoc->peer.i.init_tag = cmd->obj.u32;
+                        break;
 
                 default:
                         printk(KERN_WARNING "Impossible command: %u, %p\n",