Comment 5 for bug 1813001

Sorry Sam, I misunderstood your comment.

With the Bionic kernel, before the fix for CVE-2018-17972 ("proc: restrict kernel stack dumps to root") the behavior was:

----------------------------------------------
$ uname -r
4.15.0-38-generic
$ ls -la /proc/self/stack
-r-------- 1 ubuntu ubuntu 0 Jan 24 15:04 /proc/self/stack
$ cat /proc/self/stack
[<0>] proc_pid_stack+0xaa/0x100
[<0>] proc_single_show+0x56/0x80
[<0>] seq_read+0xe5/0x430
[<0>] __vfs_read+0x1b/0x40
[<0>] vfs_read+0x8e/0x130
[<0>] SyS_read+0x55/0xc0
[<0>] do_syscall_64+0x73/0x130
[<0>] entry_SYSCALL_64_after_hwframe+0x3d/0xa2
[<0>] 0xffffffffffffffff
----------------------------------------------

With the fix it's now:

----------------------------------------------
$ uname -r
4.15.0-44-generic
$ ls -la /proc/self/stack
-r-------- 1 ubuntu ubuntu 0 Jan 24 15:10 /proc/self/stack
$ cat /proc/self/stack
cat: /proc/self/stack: Permission denied
----------------------------------------------

So you are right, the permission on the trusty kernel (3.13) should be the same.