From: Jakub Kicinski <kuba@kernel.org>
Date: Tue, 2 Nov 2021 15:02:36 -0700
Subject: ethtool: fix ethtool msg len calculation for pause stats
Patch-mainline: v5.16-rc1
Git-commit: 1aabe578dd86e9f2867c4db4fba9a15f4ba1825d
References: jsc#SLE-15075

ETHTOOL_A_PAUSE_STAT_MAX is the MAX attribute id,
so we need to subtract non-stats and add one to
get a count (IOW -2+1 == -1).

Otherwise we'll see:

  ethnl cmd 21: calculated reply length 40, but consumed 52

Fixes: 9a27a33027f2 ("ethtool: add standard pause stats")
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Saeed Mahameed <saeedm@nvidia.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 include/linux/ethtool_netlink.h      |    3 +++
 include/uapi/linux/ethtool_netlink.h |    4 +++-
 net/ethtool/pause.c                  |    3 +--
 3 files changed, 7 insertions(+), 3 deletions(-)

--- a/include/linux/ethtool_netlink.h
+++ b/include/linux/ethtool_netlink.h
@@ -10,6 +10,9 @@
 #define __ETHTOOL_LINK_MODE_MASK_NWORDS \
 	DIV_ROUND_UP(__ETHTOOL_LINK_MODE_MASK_NBITS, 32)
 
+#define ETHTOOL_PAUSE_STAT_CNT	(__ETHTOOL_A_PAUSE_STAT_CNT -		\
+				 ETHTOOL_A_PAUSE_STAT_TX_FRAMES)
+
 enum ethtool_multicast_groups {
 	ETHNL_MCGRP_MONITOR,
 };
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -394,7 +394,9 @@ enum {
 	ETHTOOL_A_PAUSE_STAT_TX_FRAMES,
 	ETHTOOL_A_PAUSE_STAT_RX_FRAMES,
 
-	/* add new constants above here */
+	/* add new constants above here
+	 * adjust ETHTOOL_PAUSE_STAT_CNT if adding non-stats!
+	 */
 	__ETHTOOL_A_PAUSE_STAT_CNT,
 	ETHTOOL_A_PAUSE_STAT_MAX = (__ETHTOOL_A_PAUSE_STAT_CNT - 1)
 };
--- a/net/ethtool/pause.c
+++ b/net/ethtool/pause.c
@@ -67,8 +67,7 @@ static int pause_reply_size(const struct
 
 	if (req_base->flags & ETHTOOL_FLAG_STATS)
 		n += nla_total_size(0) +	/* _PAUSE_STATS */
-			nla_total_size_64bit(sizeof(u64)) *
-				(ETHTOOL_A_PAUSE_STAT_MAX - 2);
+		     nla_total_size_64bit(sizeof(u64)) * ETHTOOL_PAUSE_STAT_CNT;
 	return n;
 }