Linux vulnerability

What happened

In the Linux kernel, the following vulnerability has been resolved: cpufreq: pcc: fix use-after-free and double free in _OSC evaluation pcc_cpufreq_do_osc() calls acpi_evaluate_object() twice for the two-phase _OSC negotiation. Between the two calls it freed output.pointer but left output.length unchanged. Since acpi_evaluate_object() treats a non-zero length with a non-NULL pointer as an existing buffer to write into, the second call wrote into freed memory (use-after-free). The subsequent kfree(output.pointer) at out_free then freed the same pointer a second time (double free). Reset output.pointer to NULL and output.length to ACPI_ALLOCATE_BUFFER after freeing the first result, so ACPICA allocates a fresh buffer for each phase independently.

Affected versions

Linux: 0f1d683fb35d6c6f49ef696c95757f3970682a0e through before 8e454e9d0bc03446d610ee49abec9dfd424f6541 (git); 0f1d683fb35d6c6f49ef696c95757f3970682a0e through before 632666a63116d8061c62a988d1ca39dcd6d27c9b (git); 0f1d683fb35d6c6f49ef696c95757f3970682a0e through before 5cdb25f144b101083d8bf3fd023ad87fbe6850d7 (git); 0f1d683fb35d6c6f49ef696c95757f3970682a0e through before 982c9f92d57bda2b769851ff6d90d43dcf5f3734 (git); 0f1d683fb35d6c6f49ef696c95757f3970682a0e through before a36ca93a8ba57464e521d70a337d37f069064111 (git); 0f1d683fb35d6c6f49ef696c95757f3970682a0e through before 6ba6f6783be2ffeb2cbcdc9321c4b9f708f796f7 (git); 0f1d683fb35d6c6f49ef696c95757f3970682a0e through before 0e3c739a2f6fc1de5b19a8839ab80696b9cb2a29 (git); 0f1d683fb35d6c6f49ef696c95757f3970682a0e through before 266d3dd8b757b48a576e90f018b51f7b7563cc32 (git); 2.6.34 Fixed: See vendor advisory.

Why it matters

Review the vendor advisory and exposure of the affected product to determine operational impact.

Detection & mitigation

• Apply vendor-provided updates or mitigations.
• Review affected product exposure and access logs.