Commit b8caf69a authored Dec 21, 2022 by Krzysztof Kozlowski Committed by Greg Kroah-Hartman Jan 19, 2023

tty: serial: qcom-geni-serial: fix slab-out-of-bounds on RX FIFO buffer



Driver's probe allocates memory for RX FIFO (port->rx_fifo) based on
default RX FIFO depth, e.g. 16.  Later during serial startup the
qcom_geni_serial_port_setup() updates the RX FIFO depth
(port->rx_fifo_depth) to match real device capabilities, e.g. to 32.

The RX UART handle code will read "port->rx_fifo_depth" number of words
into "port->rx_fifo" buffer, thus exceeding the bounds.  This can be
observed in certain configurations with Qualcomm Bluetooth HCI UART
device and KASAN:

  Bluetooth: hci0: QCA Product ID   :0x00000010
  Bluetooth: hci0: QCA SOC Version  :0x400a0200
  Bluetooth: hci0: QCA ROM Version  :0x00000200
  Bluetooth: hci0: QCA Patch Version:0x00000d2b
  Bluetooth: hci0: QCA controller version 0x02000200
  Bluetooth: hci0: QCA Downloading qca/htbtfw20.tlv
  bluetooth hci0: Direct firmware load for qca/htbtfw20.tlv failed with error -2
  Bluetooth: hci0: QCA Failed to request file: qca/htbtfw20.tlv (-2)
  Bluetooth: hci0: QCA Failed to download patch (-2)
  ==================================================================
  BUG: KASAN: slab-out-of-bounds in handle_rx_uart+0xa8/0x18c
  Write of size 4 at addr ffff279347d578c0 by task swapper/0/0

  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.1.0-rt5-00350-gb2450b7e00be-dirty #26
  Hardware name: Qualcomm Technologies, Inc. Robotics RB5 (DT)
  Call trace:
   dump_backtrace.part.0+0xe0/0xf0
   show_stack+0x18/0x40
   dump_stack_lvl+0x8c/0xb8
   print_report+0x188/0x488
   kasan_report+0xb4/0x100
   __asan_store4+0x80/0xa4
   handle_rx_uart+0xa8/0x18c
   qcom_geni_serial_handle_rx+0x84/0x9c
   qcom_geni_serial_isr+0x24c/0x760
   __handle_irq_event_percpu+0x108/0x500
   handle_irq_event+0x6c/0x110
   handle_fasteoi_irq+0x138/0x2cc
   generic_handle_domain_irq+0x48/0x64

If the RX FIFO depth changes after probe, be sure to resize the buffer.

Fixes: f9d690b6 ("tty: serial: qcom_geni_serial: Allocate port->rx_fifo buffer in probe")
Cc: <stable@vger.kernel.org>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Reviewed-by: Jiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20221221164022.1087814-1-krzysztof.kozlowski@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent 5dc4c995

drivers/tty/serial/qcom_geni_serial.c

+16 −2

Original line number	Original line	Diff line number	Diff line
	@@ -864,9 +864,10 @@ static irqreturn_t qcom_geni_serial_isr(int isr, void *dev)
	return IRQ_HANDLED;		return IRQ_HANDLED;
	}		}

	static void get_tx_fifo_size(struct qcom_geni_serial_port *port)		static int setup_fifos(struct qcom_geni_serial_port *port)
	{		{
	struct uart_port *uport;		struct uart_port *uport;
			u32 old_rx_fifo_depth = port->rx_fifo_depth;

	uport = &port->uport;		uport = &port->uport;
	port->tx_fifo_depth = geni_se_get_tx_fifo_depth(&port->se);		port->tx_fifo_depth = geni_se_get_tx_fifo_depth(&port->se);
	@@ -874,6 +875,16 @@ static void get_tx_fifo_size(struct qcom_geni_serial_port *port)
	port->rx_fifo_depth = geni_se_get_rx_fifo_depth(&port->se);		port->rx_fifo_depth = geni_se_get_rx_fifo_depth(&port->se);
	uport->fifosize =		uport->fifosize =
	(port->tx_fifo_depth * port->tx_fifo_width) / BITS_PER_BYTE;		(port->tx_fifo_depth * port->tx_fifo_width) / BITS_PER_BYTE;

			if (port->rx_fifo && (old_rx_fifo_depth != port->rx_fifo_depth) && port->rx_fifo_depth) {
			port->rx_fifo = devm_krealloc(uport->dev, port->rx_fifo,
			port->rx_fifo_depth * sizeof(u32),
			GFP_KERNEL);
			if (!port->rx_fifo)
			return -ENOMEM;
			}

			return 0;
	}		}


	@@ -888,6 +899,7 @@ static int qcom_geni_serial_port_setup(struct uart_port *uport)
	u32 rxstale = DEFAULT_BITS_PER_CHAR * STALE_TIMEOUT;		u32 rxstale = DEFAULT_BITS_PER_CHAR * STALE_TIMEOUT;
	u32 proto;		u32 proto;
	u32 pin_swap;		u32 pin_swap;
			int ret;

	proto = geni_se_read_proto(&port->se);		proto = geni_se_read_proto(&port->se);
	if (proto != GENI_SE_UART) {		if (proto != GENI_SE_UART) {
	@@ -897,7 +909,9 @@ static int qcom_geni_serial_port_setup(struct uart_port *uport)

	qcom_geni_serial_stop_rx(uport);		qcom_geni_serial_stop_rx(uport);

	get_tx_fifo_size(port);		ret = setup_fifos(port);
			if (ret)
			return ret;

	writel(rxstale, uport->membase + SE_UART_RX_STALE_CNT);		writel(rxstale, uport->membase + SE_UART_RX_STALE_CNT);