Vulnerability Discussion

Exposing kernel pointers (through procfs or "seq_printf()") exposes kernel writeable structures, which may contain functions pointers. If a write vulnerability occurs in the kernel, allowing write access to any of this structure, the kernel can be compromised. This option disallows any program without the CAP_SYSLOG capability to get the addresses of kernel pointers by replacing them with "0".

Satisfies: SRG-OS-000132-GPOS-00067, SRG-OS-000433-GPOS-00192

Check

Verify that OL 9 restricts access to exposed kernel pointers with the following command:

$ sysctl kernel.kptr_restrict
kernel.kptr_restrict = 1

Fix

Configure OL 9 to prevent the leak of kernel pointers to unprivileged users.

Add or edit the following line in /etc/sysctl.d/99-sysctl.conf system configuration file:

kernel.kptr_restrict = 1

Reload settings from all system configuration files with the following command:

$ sudo sysctl --system