GHSA-559f-34rc-pgw2: Double free of an RTIO submission in the Broadcom AFBR-S50 sensor driver data-evaluation error path

The Broadcom AFBR-S50 time-of-flight sensor driver double-completes an RTIO submission when sensor data evaluation fails. In datareadyworkhandler() (drivers/sensor/broadcom/afbrs50/afbrs50.c), a non-STATUSOK return from ArgusEvaluateData() calls handleerroronresult(), which finalises the request with rtioiodevsqeerr(), but execution then fell through to the tail of the function and finalised the very same struct rtioiodevsqe a second time with rtioiodevsqeok(). Unlike the other error branches in the same function, this one did not return.

Both completion helpers reach rtioexecutordone() in subsys/rtio/rtioexecutor.c, which returns the submission to the pool via rtiosqepoolfree() and, for streaming (multishot) submissions, also releases the RX buffer with rtioreleasebuffer(). The second completion therefore reads a freed rtioiodevsqe, pushes the same mpsc node onto the submission queue while it is already on the pool free list — splicing the two lists together — and re-submits the freed request so the next measurement is written through an already-released buffer. For one-shot submissions it emits a spurious success completion carrying stale userdata and frees the same pool entry twice.

The failure branch is driven by sensor conditions rather than by host software. The vendor API documents statuses such as ERRORARGUSBIASVOLTAGEREINIT and ERRORARGUSLASERMONITORINACTIVE as transient results of harsh ambient light, so a party in front of the optical sensor can provoke the invalid-data condition without any physical contact with the board or any software access; SPI transfer errors reach the same branch. In releases before the payload.Status check was dropped, ordinary sharp distance transitions in the sensor's field of view were sufficient.

Impact is corruption of the RTIO submission pool and mempool bookkeeping: aliased submissions, writes through released buffers, and duplicate completions delivered to the application. The attacker does not control the corrupted content, so the practical consequence is memory corruption and loss of availability on devices that instantiate brcm,afbr-s50, rather than directed code execution. Only builds that enable this driver are affected.