efi: libstub: only free priv.runtime_map when allocated

priv.runtime_map is only allocated when efi_novamap is not set.
Otherwise, it is an uninitialized value.  In the error path, it is freed
unconditionally.  Avoid passing an uninitialized value to free_pool.
Free priv.runtime_map only when it was allocated.

This bug was discovered and resolved using Coverity Static Analysis
Security Testing (SAST) by Synopsys, Inc.

Fixes: f80d260 ("efi: libstub: avoid efi_get_memory_map() for allocating the virt map")
Cc: <stable@vger.kernel.org>
Signed-off-by: Hagar Hemdan <hagarhem@amazon.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>

drivers/firmware/efi/libstub/fdt.c

@@ -335,8 +335,8 @@ efi_status_t allocate_new_fdt_and_exit_boot(void *handle,
 
 fail:
 	efi_free(fdt_size, fdt_addr);
-
-	efi_bs_call(free_pool, priv.runtime_map);
+	if (!efi_novamap)
+		efi_bs_call(free_pool, priv.runtime_map);
 
 	return EFI_LOAD_ERROR;
 }