linux-kernel - [PATCH] x86: hpet: Fix to avoid potential NULL pointer dereference

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Message-Id: <20190319021958.17275-1-pakki001@umn.edu>
Date:   Mon, 18 Mar 2019 21:19:56 -0500
From:   Aditya Pakki <pakki001@....edu>
To:     pakki001@....edu
Cc:     kjlu@....edu, Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        Kees Cook <keescook@...omium.org>,
        Joe Perches <joe@...ches.com>,
        Nicolai Stange <nstange@...e.de>,
        Roland Dreier <roland@...estorage.com>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] x86: hpet: Fix to avoid potential NULL pointer dereference

hpet_virt_address may be NULL when ioremap_nocache fails. The patch
checks for such a scenario and avoids NULL pointer dereference.

Signed-off-by: Aditya Pakki <pakki001@....edu>
---
 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 dfd3aca82c61..fb32925a2e62 100644
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -905,6 +905,8 @@ 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:
-- 
2.17.1