[Vivid][SRU][PATCH] powerpc/powernv: Fix the overflow of OPAL message notifiers head array

[Chris J Arges]

From: Neelesh Gupta <neelegup at linux.vnet.ibm.com>

BugLink: http://bugs.launchpad.net/bugs/1487085

Fixes the condition check of incoming message type which can
otherwise shoot beyond the message notifiers head array.

Signed-off-by: Neelesh Gupta <neelegup at linux.vnet.ibm.com>
Reviewed-by: Vasant Hegde <hegdevasant at linux.vnet.ibm.com>
Reviewed-by: Anshuman Khandual <khandual at linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>

(backported from commit 792f96e9a769b799a2944e9369e4ea1e467135b2)
Some of this commit was merged into 9b42c07.
This backport covers the remaining parts.
Signed-off-by: Chris J Arges <chris.j.arges at canonical.com>
---
 arch/powerpc/platforms/powernv/opal.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/powerpc/platforms/powernv/opal.c b/arch/powerpc/platforms/powernv/opal.c
index 8375bf3..3f34413 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -313,6 +313,7 @@ int opal_message_notifier_register(enum opal_msg_type msg_type,
 			   __func__, msg_type);
 		return -EINVAL;
 	}
+
 	return atomic_notifier_chain_register(
 				&opal_msg_notifier_head[msg_type], nb);
 }
@@ -358,7 +359,7 @@ static void opal_handle_message(void)
 	type = be32_to_cpu(msg.msg_type);
 
 	/* Sanity check */
-	if (type > OPAL_MSG_TYPE_MAX) {
+	if (type >= OPAL_MSG_TYPE_MAX) {
 		pr_warning("%s: Unknown message type: %u\n", __func__, type);
 		return;
 	}
-- 
2.5.0