Stack overflow on SK_LOAD signature length field in Texas Instruments OMAP L138

The Texas Instruments OMAP L138 (secure variants) trusted execution environment (TEE) lacks a bounds check on the signature size field in the SK_LOAD module loading routine, present in mask ROM. A module with a sufficiently large signature field causes a stack overflow, affecting secure kernel data pages. This can be leveraged to obtain arbitrary code execution in secure supervisor context by overwriting a SHA256 function pointer in the secure kernel data area when loading a forged, unsigned SK_LOAD module encrypted with the CEK (obtainable through CVE-2022-25332). This constitutes a full break of the TEE security architecture.