gtp: Fix initialization of Flags octet in GTPv1 header

When generating a GTPv1 header in gtp1_push_header(), initialize the
'reserved' bit to zero.  All 3GPP specifications for GTPv1 from Release
99 through Release 13 agree that a transmitter shall set this bit to
zero, see e.g. Note 0 of Figure 2 in Section 6 of 3GPP TS 29.060 v13.5.0
Release 13, available from
http://www.etsi.org/deliver/etsi_ts/129000_129099/129060/13.05.00_60/ts_129060v130500p.pdf

Signed-off-by: Harald Welte <laforge@gnumonks.org>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 2 insertions, 2 deletions

diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 6031d499f2be..8b6810bad54b 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -423,11 +423,11 @@ static inline void gtp1_push_header(struct sk_buff *skb, struct pdp_ctx *pctx)
 
         /* Bits    8  7  6  5  4  3  2  1
          *        +--+--+--+--+--+--+--+--+
-         *        |version |PT| 1| E| S|PN|
+         *        |version |PT| 0| E| S|PN|
          *        +--+--+--+--+--+--+--+--+
          *          0  0  1  1  1  0  0  0
          */
-        gtp1->flags     = 0x38; /* v1, GTP-non-prime. */
+        gtp1->flags     = 0x30; /* v1, GTP-non-prime. */
         gtp1->type      = GTP_TPDU;
         gtp1->length    = htons(payload_len);
         gtp1->tid       = htonl(pctx->u.v1.o_tei);