CVE-2024-27047

What it actually does

The phy_get_internal_delay function in the Linux kernel PHY subsystem dereferences a NULL pointer when delay_values is unset and device-tree properties rx-internal-delay-ps or tx-internal-delay-ps are set to zero, resulting in a kernel oops from invalid array access.

Why it matters to the business

Systems may experience sudden kernel crashes during network interface initialization or configuration, leading to downtime on servers, embedded devices, and appliances that rely on affected kernel versions.

How an attack unfolds

An attacker with local access supplies a device-tree configuration that sets one of the delay properties to zero while omitting delay_values, triggering the flawed size check in phy_get_internal_delay and causing the NULL dereference during PHY setup.

How to fix it

Update to a Linux kernel containing commit 06dd21045a7e8bc8701b0ebedcd9a30a6325878b or later; rebuild and deploy the patched kernel on all affected systems.

How to confirm the fix worked

Confirm the running kernel contains commit 06dd21045a7e8bc8701b0ebedcd9a30a6325878b via git log or kernel version string; test PHY bring-up with the previously crashing device-tree configuration to verify absence of the oops.

Typical attack path

1. Obtain local access or the ability to influence device-tree loading
2. Configure or load a device-tree that defines rx-internal-delay-ps or tx-internal-delay-ps as zero without delay_values
3. Trigger PHY initialization that calls phy_get_internal_delay
4. Cause kernel NULL pointer dereference and system crash

How to detect it

Inspect kernel logs for NULL pointer dereference messages at virtual address 0 occurring during PHY driver initialization; search dmesg or journalctl output for phy_get_internal_delay stack traces.

What your security team should do

• Prioritize kernel updates on systems exposing network interfaces during boot
• Review device-tree sources for zero-valued delay properties
• Monitor for kernel oops reports referencing phy_get_internal_delay
• Apply the fix in all downstream kernel builds and distributions