From: Jan Glauber <jglauber@cavium.com>
Date: Mon, 12 Feb 2018 18:20:11 +0100
Subject: net: cavium: fix NULL pointer dereference in cavium_ptp_put
Patch-mainline: v4.16-rc3
Git-commit: 07a2e1cf398187814b405665b19d36425ec7a962
References: bsc#1110096

Prevent a kernel panic on reboot if ptp_clock is NULL by checking
the ptp pointer before using it.

Signed-off-by: Jan Glauber <jglauber@cavium.com>
Fixes: 8c56df372bc1 ("net: add support for Cavium PTP coprocessor")
Cc: Radoslaw Biernacki <rad@semihalf.com>
Cc: Aleksey Makarov <aleksey.makarov@cavium.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 drivers/net/ethernet/cavium/common/cavium_ptp.c |    2 ++
 1 file changed, 2 insertions(+)

--- a/drivers/net/ethernet/cavium/common/cavium_ptp.c
+++ b/drivers/net/ethernet/cavium/common/cavium_ptp.c
@@ -75,6 +75,8 @@ EXPORT_SYMBOL(cavium_ptp_get);
 
 void cavium_ptp_put(struct cavium_ptp *ptp)
 {
+	if (!ptp)
+		return;
 	pci_dev_put(ptp->pdev);
 }
 EXPORT_SYMBOL(cavium_ptp_put);