[PATCH mptcp-net 1/2] mptcp: options: mpc: avoid printing uninit data

["Matthieu Baerts (NGI0)" <matttbe@kernel.org>]

When parsing the MP_CAPABLE suboption, this pr_debug() might read and
print uninit values.

That's mostly harmless, but that's also confusing. Fixing that also
avoids some tools to complain about accessing unint data.

So read these fields only if they have been set.

Fixes: cc7972ea1932 ("mptcp: parse and emit MP_CAPABLE option according to v1 spec")
Signed-off-by: Matthieu Baerts (NGI0) <matttbe@kernel.org>
---
 net/mptcp/options.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/net/mptcp/options.c b/net/mptcp/options.c
index f87707110c75..7f7ed4753100 100644
--- a/net/mptcp/options.c
+++ b/net/mptcp/options.c
@@ -126,8 +126,11 @@ static void mptcp_parse_option(const struct sk_buff *skb,
 			ptr += 2;
 		}
 		pr_debug("MP_CAPABLE version=%x, flags=%x, optlen=%d sndr=%llu, rcvr=%llu len=%d csum=%u\n",
-			 version, flags, opsize, mp_opt->sndr_key,
-			 mp_opt->rcvr_key, mp_opt->data_len, mp_opt->csum);
+			 version, flags, opsize,
+			 opsize >= TCPOLEN_MPTCP_MPC_SYNACK ? mp_opt->sndr_key : 0,
+			 opsize >= TCPOLEN_MPTCP_MPC_ACK ? mp_opt->rcvr_key : 0,
+			 opsize >= TCPOLEN_MPTCP_MPC_ACK_DATA ? mp_opt->data_len : 0,
+			 opsize == TCPOLEN_MPTCP_MPC_ACK_DATA_CSUM ? mp_opt->csum : 0);
 		break;
 
 	case MPTCPOPT_MP_JOIN:

-- 
2.55.0