Enable support for BUG()
Ensures the running kernel is built with CONFIG_BUG=y, so BUG()/BUG_ON() assertions trigger and report critical internal errors instead of being silently ignored.
Checked against the resolved running state (e.g. sshd -T, sysctl, systemctl show), catches drop-ins and Includes a file read would miss. Caveat: runtime ≠ persistence; a value correct now may not survive a reboot.
Pavois asserts the effective configuration, the live, resolved state, not a file. File-based scanners (OVAL/SCAP, Lynis) miss Includes, drop-ins and runtime defaults; this check sees what is actually applied.
A mapping is a cross-reference to where each standard places this requirement, anchored and cross-validated, not a claim of equivalence. A passing check is evidence toward these references, how to read it.
Why this rule matters
CONFIG_BUG=y makes the kernel's BUG() and BUG_ON() macros actually trip, printing a backtrace and killing the offending context (oops/panic), when an internal invariant is violated. With it disabled, those checks are compiled out and the kernel silently continues in a corrupted state, which can mask exploitation, turn detectable faults into stealthy memory corruption, and make a security bug behave unpredictably instead of failing safe. Enabling it ensures the kernel fails loudly rather than running compromised.
What Pavois checks
Pavois reads the build-time config of the running kernel via /boot/config-$(uname -r) (fallback /proc/config.gz) and asserts CONFIG_BUG=y. Keying on uname -r reflects the exact image GRUB booted, more reliable than reading an arbitrary /boot/config-* when multiple kernels are installed.
describe command("C=/boot/config-$(uname -r); if [ -r \"$C\" ]; then cat \"$C\"; elif zcat /proc/config.gz 2>/dev/null | head -1 | grep -q .; then zcat /proc/config.gz; else echo PAVOIS_NO_KERNEL_CONFIG; fi | grep -E '^(CONFIG_BUG=|PAVOIS_NO_KERNEL_CONFIG)'") do
its('stdout') { should_not match(/PAVOIS_NO_KERNEL_CONFIG/) }
its('stdout') { should match(/^CONFIG_BUG=y$/) }
endHow to verify it is applied
Run grep -h '^CONFIG_BUG=' /boot/config-$(uname -r) (or zcat /proc/config.gz | grep '^CONFIG_BUG='). Expected: CONFIG_BUG=y.
Inspect & investigate
Static kernel build option, no dedicated log. Inspect with zcat /proc/config.gz | grep '^CONFIG_BUG=' or grep '^CONFIG_BUG=' /boot/config-$(uname -r). When BUG() actually fires at runtime, the oops/backtrace appears in dmesg and journalctl -k.
Remediation
No automated remediation is shipped: this is a kernel compile-time option. Apply it by booting a kernel built with CONFIG_BUG=y, all mainstream distribution kernels enable it by default; otherwise rebuild the kernel. pavois harden apply cannot change it.
Pavois applies this with its own harden engine, the plan below, not a shell script:
| resource | kernel_build |
|---|
pavois harden plan localwhere the target is local, a user@host SSH alias, or a container , Docs
Impact & precautions
Risk if disabled: kernel self-checks are compiled out, so corruption and invariant violations go unnoticed and the kernel may keep running in an unsafe state, masking exploits.
Precautions before changing it: this is enabled by default everywhere, so a failure is rare and usually means a custom kernel. Replacing the kernel requires a reboot, keep the prior kernel in GRUB as a fallback and validate boot on a console. Enabling CONFIG_BUG has no downside on production systems beyond a negligible code-size increase.
Standards mapping
| Standard | Reference | Type | Version | Confidence |
|---|---|---|---|---|
| ANSSI BP-028 | R19 | direct | 2.0 | high |
Each reference is a cross-reference anchored in the upstream benchmark and cross-validated against the SCAP Security Guide and ansible-lockdown, not a claim of equivalence. Direct = a prescriptive, line-level requirement; supporting = an abstract control family (NIST) the check provides evidence toward. How to read a mapping.