CVE-2026-74655

Technical Description

In the Linux kernel, the following vulnerability has been resolved:

serial: qcom-geni: fix TX DMA buffer flush

When transmit flushing a qcom-geni UART during an ongoing TX DMA, the

UART gets stuck infinitely repeating corrupted TX DMA frames.

The DMA-mode uart_ops does not provide a flush_buffer callback, so an

in-flight transfer can complete after serial core has reset the transmit

kfifo, underflowing its length and resubmitting page-sized transfers

indefinitely. Add one that stops the transfer and clears tx_remaining

and tx_queued.

The stop path was also broken: it unmapped the buffer while the serial

engine could still read it, and never reset the TX DMA state machine.

Cancel the main sequencer command first, then reset the state machine

and wait for it before unmapping. Drop the early return so a pending

mapping is also cleaned up when the main command is inactive.

The bug can be triggered from userspace with a large write immediately

followed by TCOFLUSH. A following tcdrain

Remediation

Check the references section for vendor advisories, patches, and mitigation guidance. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

References