[PATCH net-next] bnx2x: initialize ethtool info->fw_version before use

[Jonathan Toppins]

If the info->fw_version has garbage in the buffer this can lead to a BUG()
being generated in strlcat() due to the use of strlen(). Initialize the
buffer before use.

The use of a systemtap script can demonstrate the problem by injecting
garbage into fw_version:

    [root@localhost ~]# cat net-info.stp
    //
    // compile and run with command
    //# stap -g   net-info.stp
    //
    probe begin { printf("net-info  version 01.01\n")}

    function memset(msg:long) %{
    	memset((char*)STAP_ARG_msg,-1,196);
    %}

    probe module("bnx2x").function("bnx2x_get_drvinfo")
    {
      printf("In function\n");
      memset(register("rsi"));
    }

    [root@localhost ~]# stap -g net-info.stp &
    net-info  version 01.01
    [root@localhost ~]# ethtool -i eth1

Signed-off-by: Jonathan Toppins <jtoppins@xxxxxxxxxx>
---
 drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c
index 4a0ba6801c9e..49b906396dcf 100644
--- a/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c
+++ b/drivers/net/ethernet/broadcom/bnx2x/bnx2x_ethtool.c
@@ -1111,6 +1111,8 @@ static void bnx2x_get_drvinfo(struct net_device *dev,
 	int ext_dev_info_offset;
 	u32 mbi;
 
+	info->fw_version[0] = 0;
+
 	strlcpy(info->driver, DRV_MODULE_NAME, sizeof(info->driver));
 	strlcpy(info->version, DRV_MODULE_VERSION, sizeof(info->version));
 
-- 
2.16.4