ALMA-09-044790 - AlmaLinux OS 9 must clear SLUB/SLAB objects to prevent use-after-free attacks.

Information

Poisoning writes an arbitrary value to freed pages, so any modification or reference to that page after being freed or before being initialized will be detected and prevented.

This prevents many types of use-after-free vulnerabilities at some performance cost. Also prevents leak of data and detection of corrupted memory.

SLAB objects are blocks of physically contiguous memory. SLUB is the unqueued SLAB allocator.

Solution

Configure AlmaLinux OS 9 to enable poisoning of SLUB/SLAB objects with the following commands:

$ grubby --update-kernel=ALL --args="slub_debug=P"

Add or modify the following line in "/etc/default/grub" to ensure the configuration survives kernel updates:

GRUB_CMDLINE_LINUX="slub_debug=P"

See Also

https://dl.dod.cyber.mil/wp-content/uploads/stigs/zip/U_CL_AlmaLinux_OS_9_V1R1_STIG.zip

Item Details

Category: SYSTEM AND INFORMATION INTEGRITY

References: 800-53|SI-16, CAT|II, CCI|CCI-002824, Rule-ID|SV-269451r1050334_rule, STIG-ID|ALMA-09-044790, Vuln-ID|V-269451

Plugin: Unix

Control ID: d67426aa5490d9d1f33d928e923914a13a0e026e7f1103e36ffcbf351aeff3ef