[ 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 <pakki...@umn.edu>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Cc: k...@umn.edu
Cc: Borislav Petkov <b...@alien8.de>
Cc: "H. Peter Anvin" <h...@zytor.com>
Cc: Kees Cook <keesc...@chromium.org>
Cc: Joe Perches <j...@perches.com>
Cc: Nicolai Stange <nsta...@suse.de>
Cc: Roland Dreier <rol...@purestorage.com>
Link: https://lkml.kernel.org/r/20190319021958.17275-1-pakki...@umn.edu
Signed-off-by: Sasha Levin <sas...@kernel.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 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:
-- 
2.19.1



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