Executive brief
mTower is Samsung's trusted execution environment (TEE) for Arm processors, used to run sensitive operations in isolation from the main OS. A vulnerability allows an attacker on the normal (non-secure) system to crash the TEE and deny service by sending a specially crafted ioctl call with an invalid session identifier, exploiting missing null-pointer validation in the TEE's invoke handler.
Technical details
A NULL pointer dereference vulnerability exists in the tee_ioctl_invoke() function within tee/kernel/entry_std.c. The vulnerability occurs because the function does not validate the return value from tee_ta_get_session() before passing the session pointer to tee_ta_invoke_command(), which unconditionally dereferences it via sess->ctx->ops->enter_invoke_cmd(). An unauthenticated local attacker can trigger this by sending TEE_IOC_INVOKE ioctl calls with invalid, zero, or stale session identifiers, causing a NULL pointer dereference in the secure world and resulting in denial of service. The attack is reachable through the live cmse_nonsecure_entry ioctl veneer and requires no special privileges. The fix, merged in commit afef59aa6f55c5d5ebf9b14bc020bf1c2c37489a, adds proper null-pointer checks to reject invalid sessions.
Affected products
- Samsung mTower before afef59aa6f55c5d5ebf9b14bc020bf1c2c37489a
Timeline
- 2026-09-01: disclosed