ta: pkcs11: fix memory leak in close_persistent_db()

close_persistent_db() is a no-op stub that never frees the db_main and
db_objs structures allocated by init_persistent_db(). In normal TA
operation this is harmless since the TEE framework reclaims all TA
memory on unload, which is likely why it was left unimplemented.

However, the leak becomes visible when running the TA in a host-based
test environment (e.g. with AddressSanitizer) where the TEE memory
reclamation does not occur. ASan reports 264 leaked allocations
totalling ~24 KiB per TA lifecycle.

Implement close_persistent_db() to free token->db_main and
token->db_objs and NULL the pointers. Add a NULL check on the token
argument for robustness.

Fixes: c84ccd0 ("ta: pkcs11: persistent database for the pkcs11 tokens")
Signed-off-by: Georges Savoundararadj <savoundg@amazon.com>
Reviewed-by: Jerome Forissier <jerome.forissier@arm.com>

Author: manoj23

ta/pkcs11/src/persistent_token.c

@@ -286,8 +286,16 @@ enum pkcs11_rc verify_identity_auth(struct ck_token *token,
 /*
  * Release resources relate to persistent database
  */
-void close_persistent_db(struct ck_token *token __unused)
+void close_persistent_db(struct ck_token *token)
 {
+	if (!token)
+		return;
+
+	TEE_Free(token->db_main);
+	token->db_main = NULL;
+
+	TEE_Free(token->db_objs);
+	token->db_objs = NULL;
 }
 
 static int get_persistent_obj_idx(struct ck_token *token, TEE_UUID *uuid)