efi: Fix error handling in add_sysfs_runtime_map_entry()

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@oracle.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Guangyu Sun <guangyu.sun@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>

diff --git a/drivers/firmware/efi/runtime-map.c b/drivers/firmware/efi/runtime-map.c
index 87b8e3b900d2195bc44ae471003db4ad610b7d77..5c55227a34c8fd8ba0b95a6babfb28e4726da8fe 100644 (file)
--- 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);
        }
 
@@ -195,8 +197,6 @@ out_add_entry:
                entry = *(map_entries + j);
                kobject_put(&entry->kobj);
        }
-       if (map_kset)
-               kset_unregister(map_kset);
 out:
        return ret;
 }