[PATCH net] sctp: fix the issue sctp requeue auth chunk incorrectly

[Xin Long]

sctp needs to queue auth chunk back when we know that we are going
to generate another segment. But commit f1533cce60d1 ("sctp: fix
panic when sending auth chunks") requeues the last chunk processed
which is probably not the auth chunk.

It causes panic when calculating the MAC in sctp_auth_calculate_hmac(),
as the incorrect offset of the auth chunk in skb->data.

This fix is to requeue it by using packet->auth.

Fixes: f1533cce60d1 ("sctp: fix panic when sending auth chunks")
Signed-off-by: Xin Long <lucien....@gmail.com>
---
 net/sctp/output.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/sctp/output.c b/net/sctp/output.c
index 7425f6c..1f1682b 100644
--- a/net/sctp/output.c
+++ b/net/sctp/output.c
@@ -610,7 +610,8 @@ int sctp_packet_transmit(struct sctp_packet *packet, gfp_t 
gfp)
                                /* We will generate more packets, so re-queue
                                 * auth chunk.
                                 */
-                               list_add(&chunk->list, &packet->chunk_list);
+                               list_add(&packet->auth->list,
+                                        &packet->chunk_list);
                        } else {
                                sctp_chunk_free(packet->auth);
                                packet->auth = NULL;
-- 
2.1.0