CVE-2023-54053

What it actually does

Use-after-free in iwlwifi PCI driver: iwl_pci_probe failure frees the trans structure, after which iwl_pci_remove dereferences the now-NULL pointer causing kernel NULL dereference.

Why it matters to the business

Systems using affected Intel WiFi hardware may experience kernel crashes during driver load or unload sequences, resulting in unexpected reboots, loss of wireless connectivity, and operational downtime; widespread Linux kernel deployments increase exposure surface.

How an attack unfolds

An attacker with local access triggers a failed iwl_pci_probe (for example via malformed hardware state or deliberate module load timing) followed by module removal or device detach, causing iwl_pci_remove to crash the kernel; no remote unauthenticated path or named threat actors are associated with this issue.

How to fix it

Update the Linux kernel to a version containing commit f6f2d16c77f936041b8ac495fceabded4ec6c83c; rebuild and reboot into the patched kernel; for distributions, apply the vendor backport once available.

How to confirm the fix worked

Verify the running kernel contains commit f6f2d16c77f936041b8ac495fceabded4ec6c83c or later equivalent; reproduce probe-failure plus remove sequence in a test environment and confirm absence of NULL dereference oops; inspect dmesg for the fixed driver path.

Typical attack path

1. Gain local execution or module load privileges on target system
2. Force iwl_pci_probe to fail so that trans is freed
3. Trigger iwl_pci_remove (module unload, driver detach, or shutdown sequence)
4. Kernel dereferences freed pointer and panics

How to detect it

Search kernel logs (dmesg, /var/log/kern.log, journalctl) for NULL pointer dereference oops containing iwl_pci_remove; look for preceding messages indicating failed probe with crf-id or rfid errors followed by the BUG line and RIP in iwl_pci_remove.

• BUG: kernel NULL pointer dereference, address: 0000000000000028
• RIP: 0010:iwl_pci_remove+0x12/0x30 [iwlwifi]
• iwlwifi .* Detected crf-id 0xa5a5a5a2
• iwlwifi .* Can't find a correct rfid for crf id

What your security team should do

• Prioritize kernel updates on all systems containing iwlwifi hardware
• Test driver load/unload paths in staging environments before broad rollout
• Monitor for kernel oops reports matching iwl_pci_remove
• Apply vendor security updates as soon as they are released