CVE-2024-39478

What it actually does

The vulnerability occurs when kfree is called on a variable-length RSA text buffer allocated on the software stack inside the starfive crypto driver, resulting in undefined behavior and potential memory corruption.

Why it matters to the business

Systems running affected Linux kernels may experience crashes or instability during RSA operations in the starfive crypto module, leading to denial of service on devices using this hardware.

How an attack unfolds

An attacker with local access triggers RSA operations handled by the starfive driver; the driver incorrectly frees a stack buffer, causing undefined behavior that manifests as a kernel crash or memory corruption.

How to fix it

Update the Linux kernel to a version containing commit 5944de192663f272033501dcd322b008fca72006 or later; rebuild and deploy the updated kernel image on affected systems.

How to confirm the fix worked

Confirm the running kernel contains commit 5944de192663f272033501dcd322b008fca72006 via git log or kernel version string; test RSA operations in the starfive module to verify stability.

Typical attack path

1. Obtain local user access on an affected Linux system
2. Invoke RSA cryptographic operations that exercise the starfive driver
3. Trigger the erroneous kfree on the stack-allocated buffer
4. Observe resulting undefined behavior leading to denial of service

How to detect it

Inspect kernel logs for oops or panic messages referencing kfree on stack memory or starfive RSA operations; correlate with processes performing RSA operations shortly before crashes.

What your security team should do

• Prioritize patching systems that use the starfive crypto driver
• Apply the fixed commit or newer kernel release across the fleet
• Monitor for kernel oops or crashes during cryptographic workloads
• Review device configurations to limit local access where possible