fix for bnx2x panic during ethtool reporting

[Sebastian Kuzminsky]

"ethtool -i" on a bnx2x interface causes kernel panic when the
firmware version is longer than expected.  The attached patch fixes
the problem by simplifying the string handling in bnx2x_fill_fw_str().
It applies cleanly to 4.14 and 4.17-rc1.

--
Sebastian Kuzminsky
From 76ad7a41e84674519d2d5f47e42c84697ea3f23c Mon Sep 17 00:00:00 2001
From: Sebastian Kuzminsky <seb@xxxxxxxxxxx>
Date: Mon, 16 Apr 2018 23:24:07 +0000
Subject: [PATCH] bnx2x: make fw str in a non-crazy way

This fixes an unterminated string bug when the firwmare version
(bp->fw_ver) is longer than the passed-in buffer (buf/buf_len).
---
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
index 67fe3d826566..5534cee0aab8 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_cmn.c
@@ -150,9 +150,9 @@ void bnx2x_fill_fw_str(struct bnx2x *bp, char *buf, size_t buf_len)
 		phy_fw_ver[0] = '\0';
 		bnx2x_get_ext_phy_fw_version(&bp->link_params,
 					     phy_fw_ver, PHY_FW_VER_LEN);
-		strlcpy(buf, bp->fw_ver, buf_len);
-		snprintf(buf + strlen(bp->fw_ver), 32 - strlen(bp->fw_ver),
-			 "bc %d.%d.%d%s%s",
+		snprintf(buf, buf_len,
+			 "%s bc %d.%d.%d%s%s",
+			 bp->fw_ver,
 			 (bp->common.bc_ver & 0xff0000) >> 16,
 			 (bp->common.bc_ver & 0xff00) >> 8,
 			 (bp->common.bc_ver & 0xff),
-- 
2.11.0