serial: qcom-geni: do not advance stale DMA completions
In the Linux kernel, the following vulnerability has been resolved: serial: qcom-geni: do not advance stale DMA completions The qcom GENI serial DMA TX completion path advances the transmit fifo by the number of bytes recorded in port->tx_remaining. If uart_flush_buffer() runs after the hardware has completed a DMA transfer but before the DMA completion interrupt has been handled, the serial core resets the transmit fifo while port->tx_remaining still describes the old DMA transfer. A previous fix avoided advancing an empty fifo by checking that the fifo length is at least tx_remaining. That still does not distinguish the old DMA payload