From 12e3c0433e8a3b817fbb978a1be973a04cd5d6f3 Mon Sep 17 00:00:00 2001
From: Kees Cook <keescook@chromium.org>
Date: Mon, 15 May 2017 14:26:40 -0700
Subject: [PATCH] libertas: Avoid reading past end of buffer
Git-commit: 12e3c0433e8a3b817fbb978a1be973a04cd5d6f3
Patch-mainline: v4.13-rc1
References: FATE#326294

Using memcpy() from a string that is shorter than the length copied means
the destination buffer is being filled with arbitrary data from the kernel
rodata segment. Instead, redefine the stat strings to be ETH_GSTRING_LEN
sizes, like other drivers. This lets us use a single memcpy that does not
leak rodata contents. Additionally adjust indentation to keep checkpatch.pl
happy.

This was found with the future CONFIG_FORTIFY_SOURCE feature.

Cc: Daniel Micay <danielmicay@gmail.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/net/wireless/marvell/libertas/mesh.c | 26 ++++++++------------
 1 file changed, 10 insertions(+), 16 deletions(-)

diff --git a/drivers/net/wireless/marvell/libertas/mesh.c b/drivers/net/wireless/marvell/libertas/mesh.c
index d0c881dd5846..2229fb448189 100644
--- a/drivers/net/wireless/marvell/libertas/mesh.c
+++ b/drivers/net/wireless/marvell/libertas/mesh.c
@@ -1108,15 +1108,15 @@ void lbs_mesh_set_txpd(struct lbs_private *priv,
  * Ethtool related
  */
 
-static const char * const mesh_stat_strings[] = {
-			"drop_duplicate_bcast",
-			"drop_ttl_zero",
-			"drop_no_fwd_route",
-			"drop_no_buffers",
-			"fwded_unicast_cnt",
-			"fwded_bcast_cnt",
-			"drop_blind_table",
-			"tx_failed_cnt"
+static const char mesh_stat_strings[MESH_STATS_NUM][ETH_GSTRING_LEN] = {
+	"drop_duplicate_bcast",
+	"drop_ttl_zero",
+	"drop_no_fwd_route",
+	"drop_no_buffers",
+	"fwded_unicast_cnt",
+	"fwded_bcast_cnt",
+	"drop_blind_table",
+	"tx_failed_cnt"
 };
 
 void lbs_mesh_ethtool_get_stats(struct net_device *dev,
@@ -1170,17 +1170,11 @@ int lbs_mesh_ethtool_get_sset_count(struct net_device *dev, int sset)
 void lbs_mesh_ethtool_get_strings(struct net_device *dev,
 	uint32_t stringset, uint8_t *s)
 {
-	int i;
-
 	lbs_deb_enter(LBS_DEB_ETHTOOL);
 
 	switch (stringset) {
 	case ETH_SS_STATS:
-		for (i = 0; i < MESH_STATS_NUM; i++) {
-			memcpy(s + i * ETH_GSTRING_LEN,
-					mesh_stat_strings[i],
-					ETH_GSTRING_LEN);
-		}
+		memcpy(s, mesh_stat_strings, sizeof(mesh_stat_strings));
 		break;
 	}
 	lbs_deb_enter(LBS_DEB_ETHTOOL);
-- 
2.19.2