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

[Tobin C. Harding]

On Tue, Oct 10, 2017 at 09:06:50PM -0700, Joe Perches wrote:
> 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;
> }
> 

Nice.

thanks,
Tobin.