[PATCH 5.15 769/917] ethtool: fix ethtool msg len calculation for pause stats

Greg Kroah-Hartman
2021-11-16T00:01:02Z

From: Jakub Kicinski <kuba@kernel.org>

[ Upstream commit 1aabe578dd86e9f2867c4db4fba9a15f4ba1825d ]

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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
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(-)

diff --git a/include/linux/ethtool_netlink.h b/include/linux/ethtool_netlink.h
index 1e7bf78cb3829..aba348d58ff61 100644
--- 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,
};
diff --git a/include/uapi/linux/ethtool_netlink.h b/include/uapi/linux/ethtool_netlink.h
index 5545f1ca9237c..f7204bdfe8db1 100644
--- a/include/uapi/linux/ethtool_netlink.h
+++ b/include/uapi/linux/ethtool_netlink.h
@@ -407,7 +407,9 @@ 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)
};
diff --git a/net/ethtool/pause.c b/net/ethtool/pause.c
index 9009f412151e7..ee1e5806bc93a 100644
--- a/net/ethtool/pause.c
+++ b/net/ethtool/pause.c
@@ -56,8 +56,7 @@ static int pause_reply_size(const struct ethnl_req_info *req_base,

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;
}

--
2.33.0