New behavior with Trusty kernel 3.13.0-166-generic:
ubuntu@autopkgtest:~$ ls -la /proc/self/stack -r-------- 1 ubuntu ubuntu 0 Mar 6 15:43 /proc/self/stack ubuntu@autopkgtest:~$ cat /proc/self/stack cat: /proc/self/stack: Permission denied
New behavior with Trusty kernel 3.13.0-166-generic:
ubuntu@ autopkgtest: ~$ ls -la /proc/self/stack autopkgtest: ~$ cat /proc/self/stack
-r-------- 1 ubuntu ubuntu 0 Mar 6 15:43 /proc/self/stack
ubuntu@
cat: /proc/self/stack: Permission denied