From: Aditya Pakki <pakki001@umn.edu>
Date: Tue, 19 Mar 2019 02:19:56 +0000 (-0500)
Subject: x86/hpet: Prevent potential NULL pointer dereference
X-Git-Tag: v4.9.170~29
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=ec1fdc02cc255f5021f52e3bf90044099d9eba67;p=thirdparty%2Fkernel%2Fstable.git

x86/hpet: Prevent potential NULL pointer dereference

[ Upstream commit 2e84f116afca3719c9d0a1a78b47b48f75fd5724 ]

hpet_virt_address may be NULL when ioremap_nocache fail, but the code lacks
a check.

Add a check to prevent NULL pointer dereference.

Signed-off-by: Aditya Pakki <pakki001@umn.edu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: kjlu@umn.edu
Cc: Borislav Petkov <bp@alien8.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Joe Perches <joe@perches.com>
Cc: Nicolai Stange <nstange@suse.de>
Cc: Roland Dreier <roland@purestorage.com>
Link: https://lkml.kernel.org/r/20190319021958.17275-1-pakki001@umn.edu
Signed-off-by: Sasha Levin <sashal@kernel.org>
---

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index 756634f14df68..775c23d4021a2 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -914,6 +914,8 @@ int __init hpet_enable(void)
 		return 0;
 
 	hpet_set_mapping();
+	if (!hpet_virt_address)
+		return 0;
 
 	/*
 	 * Read the period and check for a sane value: