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 319bcb9372fed3817cf6a3c16dfd38cb35a312a1..3e9c5725732fc56d22a423e04c1dd2791ff2be6a 100644 (file)
--- a/arch/x86/kernel/hpet.c
+++ b/arch/x86/kernel/hpet.c
@@ -799,6 +799,8 @@ 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: