Local privilege escalation via QAT DH heap overflow

Heap corruption in the Linux QAT Diffie-Hellman path allows local users to gain kernel privileges through oversized shared-secret input. In qat_dh_compute_value, a source length larger than the key size underflows a subtraction before scatterlist data is copied into a linear heap buffer. Exploitation requires local syscall access and compatible Intel QAT hardware selecting qat-dh, enabling kernel memory corruption, a panic, or privilege escalation.