[wfn]

No, it would seem (I'm not sure though) that this happens for you because your distro is smart enough to have a nice security setting be on by default. The setting / sysctl can be changed at:

  /proc/sys/kernel/kptr_restrict

For me, this gave me 0, but if you cat this it should give you 1. So essentially it's a setting but I'd wager it's not related to you remounting /proc.

Just for curiosity's sake, from searching around it seems that this particular security feature (hide kernel pointers for unprivileged users) seems to have originated from this commit (which in itself implements a broader and more general security feature): http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.g... - but it's often not enabled.

So it's not ASLR or anything to do with filesystem options (per se), but rather a custom "kptr_restrict" kernel vs. userspace security feature provided by the kernel:

"[...] The %pK format specifier is designed to hide exposed kernel pointers, specifically via /proc interfaces. Exposing these pointers provides an easy target for kernel write vulnerabilities, since they reveal the locations of writable structures containing easily triggerable function pointers." (Dan Rosenberg, 2011-01-13 - nice.) (Of course if there's no ASLR and one knows which distro is being targeted, it's possible to find those values on another machine and to just bake them into the exploit, as others have pointed out. Also, other channels exist for finding these addresses, etc.)