From 2962aecef2878e2192ac9676700469678507c24d Mon Sep 17 00:00:00 2001
From: Hans-Frieder Vogt
Date: Sun, 6 Oct 2013 21:13:35 +0200
Subject: w1 - fix fops in w1_bus_notify

Introduce a check to make sure that fops are only called if they have
been defined by the slave module.

Without this check modules like w1_smem cause a NULL pointer dereference
bug.

Signed-off by: Hans-Frieder Vogt <hfvogt@gmx.net>
Acked-by: Evgeniy Polyakov <zbr@ioremap.net>
Cc: stable <stable@vger.kernel.org> # 3.11+

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/w1/w1.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/w1/w1.c b/drivers/w1/w1.c
index c7c64f18773d..0781217d2396 100644
--- a/drivers/w1/w1.c
+++ b/drivers/w1/w1.c
@@ -613,6 +613,9 @@ static int w1_bus_notify(struct notifier_block *nb, unsigned long action,
 	sl = dev_to_w1_slave(dev);
 	fops = sl->family->fops;
 
+	if (!fops)
+		return 0;
+
 	switch (action) {
 	case BUS_NOTIFY_ADD_DEVICE:
 		/* if the family driver needs to initialize something... */
-- 
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