[PATCH 4.17 081/324] sctp: fix erroneous inc of snmp SctpFragUsrMsgs

[Greg Kroah-Hartman]

4.17-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>

[ Upstream commit fedb1bd3d274b33c432cb83c80c6b3cf54d509c8 ]

Currently it is incrementing SctpFragUsrMsgs when the user message size
is of the exactly same size as the maximum fragment size, which is wrong.

The fix is to increment it only when user message is bigger than the
maximum fragment size.

Fixes: bfd2e4b8734d ("sctp: refactor sctp_datamsg_from_user")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@xxxxxxxxx>
Acked-by: Neil Horman <nhorman@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/sctp/chunk.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/sctp/chunk.c
+++ b/net/sctp/chunk.c
@@ -247,7 +247,9 @@ struct sctp_datamsg *sctp_datamsg_from_u
 	/* Account for a different sized first fragment */
 	if (msg_len >= first_len) {
 		msg->can_delay = 0;
-		SCTP_INC_STATS(sock_net(asoc->base.sk), SCTP_MIB_FRAGUSRMSGS);
+		if (msg_len > first_len)
+			SCTP_INC_STATS(sock_net(asoc->base.sk),
+				       SCTP_MIB_FRAGUSRMSGS);
 	} else {
 		/* Which may be the only one... */
 		first_len = msg_len;