CVE-2026-99024 in Linux
Summary
by MITRE • 10/23/2026
In the Linux kernel, the following vulnerability has been resolved:
optee: register TEE devices only once fully initialized
optee_probe() called tee_device_register() on both the client and the supplicant device before the rest of struct optee had been initialized.
tee_device_register() calls cdev_device_add(), which does two things at once: it creates /dev/tee0 and /dev/teepriv0, and it links the device into the tee class so that class_find_device() can find it. From that moment on the device is reachable both from user space via tee_open() and from kernel space via tee_client_open_context(). The only gate in teedev_open() is tee_device_get(), which merely checks that teedev->desc is non-NULL, which was already set by tee_device_alloc(). Therefore, there is effectively no gate at all.
A context opened in that window can run against a struct optee where
- optee->call_queue.mutex is not initialized by optee_cq_init() - optee->supp mutex and completions is not initialized by optee_supp_init() - optee->rpmb_dev_mutex is not initialized yet, - the message argument cache is not initialized by optee_shm_arg_cache_init() - optee->ctx is still NULL
Any open session or invoke during this window takes uninitialized mutexes and dereferences a NULL pointer.
Fix it by moving both tee_device_register() calls down to the point where all of struct optee is set up.
[JW: adding fixes and cc]
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