Re: [PATCH 1/4] lib/dynamic_debug: add NULL check after kstrdup

[Andrew Morton]

On Mon, 29 Jun 2026 16:30:51 +0700 Martin Weiss <martin.githubacc@xxxxxxxxx> wrote:

> kstrdup(saved_command_line, GFP_KERNEL) may return NULL under memory
> pressure. Add a check to avoid NULL pointer dereference during boot-time
> dynamic debug parameter parsing.
> 

Thanks.

> --- a/lib/dynamic_debug.c
> +++ b/lib/dynamic_debug.c
> @@ -1479,6 +1479,8 @@ static int __init dynamic_debug_init(void)
>  	 * slightly noisy if verbose, but harmless.
>  	 */
>  	cmdline = kstrdup(saved_command_line, GFP_KERNEL);
> +	if (!cmdline)
> +		return 0; /* prevents a boot-time NULL deref */
>  	parse_args("dyndbg params", cmdline, NULL,
>  		   0, 0, 0, NULL, &ddebug_dyndbg_boot_param_cb);
>  	kfree(cmdline);

We conventionally assume that memory allocations at __init time cannot
fail.  Sashiko explains why ;)

	https://sashiko.dev/#/patchset/20260629093056.591498-1-Martin.weiss2410@xxxxxxxxx