From 0aa82c482ab2ece530a6f44897b63b274bb43c8e Mon Sep 17 00:00:00 2001
From: Nathan Lynch <nathanl@linux.ibm.com>
Date: Fri, 7 Jun 2019 00:04:07 -0500
Subject: [PATCH] powerpc/pseries: Fix oops in hotplug memory notifier

References: bsc#1138375, LTC#178204
Patch-mainline: v5.3-rc1
Git-commit: 0aa82c482ab2ece530a6f44897b63b274bb43c8e

During post-migration device tree updates, we can oops in
pseries_update_drconf_memory() if the source device tree has an
ibm,dynamic-memory-v2 property and the destination has a
ibm,dynamic_memory (v1) property. The notifier processes an "update"
for the ibm,dynamic-memory property but it's really an add in this
scenario. So make sure the old property object is there before
dereferencing it.

Fixes: 2b31e3aec1db ("powerpc/drmem: Add support for ibm, dynamic-memory-v2 property")
Cc: stable@vger.kernel.org # v4.16+
Signed-off-by: Nathan Lynch <nathanl@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/platforms/pseries/hotplug-memory.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/powerpc/platforms/pseries/hotplug-memory.c b/arch/powerpc/platforms/pseries/hotplug-memory.c
index 47087832f8b2..e6bd172bcf30 100644
--- a/arch/powerpc/platforms/pseries/hotplug-memory.c
+++ b/arch/powerpc/platforms/pseries/hotplug-memory.c
@@ -980,6 +980,9 @@ static int pseries_update_drconf_memory(struct of_reconfig_data *pr)
 	if (!memblock_size)
 		return -EINVAL;
 
+	if (!pr->old_prop)
+		return 0;
+
 	p = (__be32 *) pr->old_prop->value;
 	if (!p)
 		return -EINVAL;
-- 
2.21.0