Re: [PATCH v2] panic: prevent panic_timeout * 1000 from overflow

[Matthew Wilcox]

On Mon, Jul 13, 2020 at 06:57:39PM -0700, Andrew Morton wrote:
> +++ a/kernel/panic.c
> @@ -313,13 +313,16 @@ void panic(const char *fmt, ...)
>  		 * Delay timeout seconds before rebooting the machine.
>  		 * We can't use the "normal" timers since we just panicked.
>  		 */
> +		u64 timeout = panic_timeout * 1000;	/* avoid overflow */

1000ULL to not truncate before the assignment.

> +		u64 timer;

... as you implied later

		u64 timer, timer_next;

> (untested)

Well, there's the rub.  Testing requires 49 days (2^32 / 1000 seconds).