KEYS: trusted: Rollback init_trusted() consistently

Do bind neither static calls nor trusted_key_exit() before a successful
init, in order to maintain a consistent state. In addition, depart the
init_trusted() in the case of a real error (i.e. getting back something
else than -ENODEV).

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Closes: https://lore.kernel.org/linux-integrity/CAHk-=whOPoLaWM8S8GgoOPT7a2+nMH5h3TLKtn=R_3w4R1_Uvg@mail.gmail.com/
Cc: stable@vger.kernel.org # v5.13+
Fixes: 5d0682b ("KEYS: trusted: Add generic trusted keys framework")
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>

Author: jarkkojs

security/keys/trusted-keys/trusted_core.c

@@ -358,17 +358,17 @@ static int __init init_trusted(void)
 		if (!get_random)
 			get_random = kernel_get_random;
 
-		static_call_update(trusted_key_seal,
-				   trusted_key_sources[i].ops->seal);
-		static_call_update(trusted_key_unseal,
-				   trusted_key_sources[i].ops->unseal);
-		static_call_update(trusted_key_get_random,
-				   get_random);
-		trusted_key_exit = trusted_key_sources[i].ops->exit;
-		migratable = trusted_key_sources[i].ops->migratable;
-
 		ret = trusted_key_sources[i].ops->init();
-		if (!ret)
+		if (!ret) {
+			static_call_update(trusted_key_seal, trusted_key_sources[i].ops->seal);
+			static_call_update(trusted_key_unseal, trusted_key_sources[i].ops->unseal);
+			static_call_update(trusted_key_get_random, get_random);
+
+			trusted_key_exit = trusted_key_sources[i].ops->exit;
+			migratable = trusted_key_sources[i].ops->migratable;
+		}
+
+		if (!ret || ret != -ENODEV)
 			break;
 	}