Commit 0d6bf63e authored Nov 29, 2022 by Johan Hovold Committed by Greg Kroah-Hartman Jan 18, 2023

USB: serial: f81232: fix division by zero on line-speed change



commit a08ca6ebafe615c9028c53fc4c9e6c9b2b1f2888 upstream.

The driver leaves the line speed unchanged in case a requested speed is
not supported. Make sure to handle the case where the current speed is
B0 (hangup) without dividing by zero when determining the clock source.

Fixes: 268ddb5e ("USB: serial: f81232: add high baud rate support")
Cc: stable@vger.kernel.org      # 5.2
Cc: Ji-Ze Hong (Peter Hong) <hpeter@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent fe0f2143

drivers/usb/serial/f81232.c

+7 −5

Original line number	Diff line number	Diff line
		@@ -78,9 +78,6 @@ static u8 const clock_table[] = { F81232_CLK_1_846_MHZ, F81232_CLK_14_77_MHZ,

		static int calc_baud_divisor(speed_t baudrate, speed_t clockrate)
		{
		if (!baudrate)
		return 0;

		return DIV_ROUND_CLOSEST(clockrate, baudrate);
		}

		@@ -423,9 +420,14 @@ static void f81232_set_baudrate(struct tty_struct *tty,
		speed_t baud_list[] = { baudrate, old_baudrate, F81232_DEF_BAUDRATE };

		for (i = 0; i < ARRAY_SIZE(baud_list); ++i) {
		idx = f81232_find_clk(baud_list[i]);
		if (idx >= 0) {
		baudrate = baud_list[i];
		if (baudrate == 0) {
		tty_encode_baud_rate(tty, 0, 0);
		return;
		}

		idx = f81232_find_clk(baudrate);
		if (idx >= 0) {
		tty_encode_baud_rate(tty, baudrate, baudrate);
		break;
		}