From: Prarit Bhargava <prarit@redhat.com>
Date: Wed, 31 May 2017 13:32:00 -0400
Subject: [PATCH] acpi/nfit: Fix memory corruption/Unregister mce decoder on
 failure
References: bnc#1060662
Patch-mainline: v4.12.4
Git-commit: 7e700d2c59e5853c9126642976b4f5768f64c9b3

commit 7e700d2c59e5853c9126642976b4f5768f64c9b3 upstream.

nfit_init() calls nfit_mce_register() on module load.  When the module
load fails the nfit mce decoder is not unregistered.  The module's
memory is freed leaving the decoder chain referencing junk.  This will
cause panics as future registrations will reference the free'd memory.

Unregister the nfit mce decoder on module init failure.

[v2]: register and then unregister mce handler to avoid losing mce events
[v3]: also cleanup nfit workqueue

Fixes: 6839a6d96f4e ("nfit: do an ARS scrub on hitting a latent media error")
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Len Brown <lenb@kernel.org>
Cc: Vishal Verma <vishal.l.verma@intel.com>
Cc: "Lee, Chun-Yi" <joeyli.kernel@gmail.com>
Cc: Linda Knippers <linda.knippers@hpe.com>
Cc: lszubowi@redhat.com
Acked-by: Jeff Moyer <jmoyer@redhat.com>
Signed-off-by: Prarit Bhargava <prarit@redhat.com>
Reviewed-by: Vishal Verma <vishal.l.verma@intel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
 drivers/acpi/nfit/core.c | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/drivers/acpi/nfit/core.c b/drivers/acpi/nfit/core.c
index 656acb5d7166..f3c3e9d4563c 100644
--- a/drivers/acpi/nfit/core.c
+++ b/drivers/acpi/nfit/core.c
@@ -3043,6 +3043,8 @@ static struct acpi_driver acpi_nfit_driver = {
 
 static __init int nfit_init(void)
 {
+	int ret;
+
 	BUILD_BUG_ON(sizeof(struct acpi_table_nfit) != 40);
 	BUILD_BUG_ON(sizeof(struct acpi_nfit_system_address) != 56);
 	BUILD_BUG_ON(sizeof(struct acpi_nfit_memory_map) != 48);
@@ -3070,8 +3072,14 @@ static __init int nfit_init(void)
 		return -ENOMEM;
 
 	nfit_mce_register();
+	ret = acpi_bus_register_driver(&acpi_nfit_driver);
+	if (ret) {
+		nfit_mce_unregister();
+		destroy_workqueue(nfit_wq);
+	}
+
+	return ret;
 
-	return acpi_bus_register_driver(&acpi_nfit_driver);
 }
 
 static __exit void nfit_exit(void)
-- 
2.14.2