linux-kernel - [PATCH 4.19 044/110] x86/hpet: Prevent potential NULL pointer dereference

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Date:   Thu, 18 Apr 2019 19:56:33 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Aditya Pakki <pakki001@....edu>,
        Thomas Gleixner <tglx@...utronix.de>, kjlu@....edu,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>,
        Kees Cook <keescook@...omium.org>,
        Joe Perches <joe@...ches.com>,
        Nicolai Stange <nstange@...e.de>,
        Roland Dreier <roland@...estorage.com>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.19 044/110] 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@....edu>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: kjlu@....edu
Cc: Borislav Petkov <bp@...en8.de>
Cc: "H. Peter Anvin" <hpa@...or.com>
Cc: Kees Cook <keescook@...omium.org>
Cc: Joe Perches <joe@...ches.com>
Cc: Nicolai Stange <nstange@...e.de>
Cc: Roland Dreier <roland@...estorage.com>
Link: https://lkml.kernel.org/r/20190319021958.17275-1-pakki001@umn.edu
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 arch/x86/kernel/hpet.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c
index b0acb22e5a46..1e3f1f140ffb 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -909,6 +909,8 @@ 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:
-- 
2.19.1