Messages in this thread | | | Date | Thu, 18 Nov 2010 09:12:41 +0100 | From | Ingo Molnar <> | Subject | Re: [PATCH] kernel/time: Make /proc/timer_list mode 0400 |
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* Thomas Gleixner <tglx@linutronix.de> wrote:
> On Wed, 17 Nov 2010, Andrew Morton wrote: > > > On Wed, 17 Nov 2010 18:18:32 +0100 > > Peter Zijlstra <a.p.zijlstra@chello.nl> wrote: > > > > > On Wed, 2010-11-17 at 18:08 +0100, Marcus Meissner wrote: > > > > Hi, > > > > > > > > /proc/timer_list contains kernel addresses, like e.g.: > > > > #0: <c000000001404158>, tick_sched_timer, S:01, .tick_nohz_restart_sched_tick, swapper/0 > > > > ... > > > > > > > > Avoid leaking them to user space to make writing kernel exploits a bit harder. > > > > > > > > (I currently cannot think of a userland tool that uses this, this is > > > > likely pretty much root-only.) > > > > > > iirc powertop parses this.. > > > > I bet it doesn't look at the kernel address (why was that added in the > > first place, anyway?) > > > > I'd suggest that the risk of breakage would be much less if we left the > > file permissions alone and arranged for those addresses to be > > 0000000000000000 for non-root readers. > > You beat me to it. Having the full information is quite helpful at > times.
We should do something like:
if (!capable(CAP_SYS_ADMIN)) print_ptr = NULL;
sprintf(s, "%p", print_ptr);
Thanks,
Ingo
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