[PATCH] Fix race in efi variable delete code.

[Prarit Bhargava <prarit@redhat.com>]

Fix race when deleting an EFI variable and issuing another EFI command on the
same variable.  The removal of the variable from the efivars_list should be
done in efivar_delete and not delayed until the kprobes release.

Signed-off-by: Prarit Bhargava <prarit@redhat.com>

diff --git a/drivers/firmware/efivars.c b/drivers/firmware/efivars.c
index 5ab5e39..bf2ca97 100644
--- a/drivers/firmware/efivars.c
+++ b/drivers/firmware/efivars.c
@@ -385,10 +385,8 @@ static struct sysfs_ops efivar_attr_ops = {
 
 static void efivar_release(struct kobject *kobj)
 {
-	struct efivar_entry *var = container_of(kobj, struct efivar_entry, kobj);
-	spin_lock(&efivars_lock);
-	list_del(&var->list);
-	spin_unlock(&efivars_lock);
+	struct efivar_entry *var = container_of(kobj, struct efivar_entry,
+						kobj);
 	kfree(var);
 }
 
@@ -537,6 +535,9 @@ efivar_delete(struct subsystem *sub, const char *buf, size_t count)
 		spin_unlock(&efivars_lock);
 		return -EIO;
 	}
+
+	list_del(&search_efivar->list);
+
 	/* We need to release this lock before unregistering. */
 	spin_unlock(&efivars_lock);