Re: [PATCH] printk: hash addresses printed with %p

[Joe Perches <joe@perches.com>]

On Wed, 2017-10-11 at 14:48 +1100, Tobin C. Harding wrote:
> Currently there are many places in the kernel where addresses are being
> printed using an unadorned %p. Kernel pointers should be printed using
> %pK allowing some control via the kptr_restrict sysctl. Exposing addresses
> gives attackers sensitive information about the kernel layout in memory.
[]
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
[]
> @@ -1591,6 +1591,35 @@ char *device_node_string(char *buf, char *end, struct device_node *dn,
>  	return widen_string(buf, buf - buf_start, end, spec);
>  }
>  
> +static long get_random_odd_long(void)
> +{
> +	long val = 0;
> +
> +	while((val & 1) == 0) {
> +		val = get_random_long();
> +	}
> +
> +	return val;
> +}

Perhaps

static long get_random_odd_long(void)
{
	return get_random_long() | 1L;
}