CVE-2024-56773

What it actually does

kunit_kzalloc() may return NULL in kunit_device_driver_test(); the pointer is dereferenced without a check, resulting in a NULL pointer dereference (kernel crash or undefined behavior) in the KUnit testing framework.

Why it matters to the business

Kernel instability or crashes during test execution in development or CI environments; low production risk but can disrupt kernel validation workflows on affected systems.

How an attack unfolds

An attacker with the ability to load and execute the specific KUnit test module triggers kunit_device_driver_test(); when kunit_kzalloc() returns NULL the subsequent dereference causes a kernel oops. No remote or unauthenticated path exists; requires test code execution context.

How to fix it

Apply the upstream fix that adds a NULL check after kunit_kzalloc(); update to a kernel containing the resolution. For listed chromium-browser packages on Ubuntu 14.04 LTS upgrade to 53.0.2785.143-0ubuntu0.14.04.1.1142 or newer.

How to confirm the fix worked

Confirm the NULL check is present in kunit_device_driver_test() after kunit_kzalloc(); run the test under memory-pressure conditions and verify no oops occurs; check kernel version or package version against the fixed release.

Typical attack path

1. Gain ability to load/execute KUnit test modules on the target kernel
2. Invoke or schedule kunit_device_driver_test()
3. Force kunit_kzalloc() to return NULL (resource pressure or allocator behavior)
4. Trigger NULL dereference leading to kernel panic or denial of service

How to detect it

Review kernel logs (dmesg, /var/log/kern.log) for NULL pointer dereference oops mentioning kunit_device_driver_test or kunit_kzalloc; inspect test execution logs for unexpected panics during KUnit runs.

What your security team should do

• Prioritize patching kernels that run KUnit tests in CI or development fleets
• Update chromium-browser packages on Ubuntu 14.04 LTS to the stated fixed version
• Monitor for kernel oops reports referencing kunit_device_driver_test