[PATCH 3.16.y-ckt 091/129] efi: Fix error handling in add_sysfs_runtime_map_entry()

[Luis Henriques]

3.16.7-ckt12 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@xxxxxxxxxx>

commit d67e199611b986b345ea3087ee2e4a15da1c98b3 upstream.

I spotted two (difficult to hit) bugs while reviewing this.

1)  There is a double free bug because we unregister "map_kset" in
    add_sysfs_runtime_map_entry() and also efi_runtime_map_init().
2)  If we fail to allocate "entry" then we should return
    ERR_PTR(-ENOMEM) instead of NULL.

Signed-off-by: Dan Carpenter <dan.carpenter@xxxxxxxxxx>
Cc: Dave Young <dyoung@xxxxxxxxxx>
Cc: Guangyu Sun <guangyu.sun@xxxxxxxxxx>
Signed-off-by: Matt Fleming <matt.fleming@xxxxxxxxx>
Signed-off-by: Luis Henriques <luis.henriques@xxxxxxxxxxxxx>
---
 drivers/firmware/efi/runtime-map.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/firmware/efi/runtime-map.c b/drivers/firmware/efi/runtime-map.c
index c98b101a73ae..019a7e32de4c 100644
--- a/drivers/firmware/efi/runtime-map.c
+++ b/drivers/firmware/efi/runtime-map.c
@@ -120,7 +120,8 @@ add_sysfs_runtime_map_entry(struct kobject *kobj, int nr)
 	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
 	if (!entry) {
 		kset_unregister(map_kset);
-		return entry;
+		map_kset = NULL;
+		return ERR_PTR(-ENOMEM);
 	}
 
 	memcpy(&entry->md, efi_runtime_map + nr * efi_memdesc_size,
@@ -132,6 +133,7 @@ add_sysfs_runtime_map_entry(struct kobject *kobj, int nr)
 	if (ret) {
 		kobject_put(&entry->kobj);
 		kset_unregister(map_kset);
+		map_kset = NULL;
 		return ERR_PTR(ret);
 	}
 
@@ -174,8 +176,6 @@ out_add_entry:
 		entry = *(map_entries + j);
 		kobject_put(&entry->kobj);
 	}
-	if (map_kset)
-		kset_unregister(map_kset);
 out:
 	return ret;
 }
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