Commit 6d943580 authored Nov 29, 2022 by Johan Hovold Committed by sanglipeng Jul 31, 2023

USB: serial: f81534: fix division by zero on line-speed change

stable inclusion
from stable-v5.10.161
commit c8bf31a00f4f921259d950f1984fbea518eba557
category: bugfix
bugzilla: https://gitee.com/openeuler/kernel/issues/I7P7OH

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=c8bf31a00f4f921259d950f1984fbea518eba557



--------------------------------

commit 188c9c2e 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: 3aacac02 ("USB: serial: f81534: add high baud rate support")
Cc: stable@vger.kernel.org      # 4.16
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>
Signed-off-by: sanglipeng <sanglipeng1@jd.com>

parent a3cf5bc6

drivers/usb/serial/f81534.c

+7 −5

Original line number	Diff line number	Diff line
		@@ -538,9 +538,6 @@ static int f81534_submit_writer(struct usb_serial_port *port, gfp_t mem_flags)

		static u32 f81534_calc_baud_divisor(u32 baudrate, u32 clockrate)
		{
		if (!baudrate)
		return 0;

		/* Round to nearest divisor */
		return DIV_ROUND_CLOSEST(clockrate, baudrate);
		}
		@@ -570,9 +567,14 @@ static int f81534_set_port_config(struct usb_serial_port *port,
		u32 baud_list[] = {baudrate, old_baudrate, F81534_DEFAULT_BAUD_RATE};

		for (i = 0; i < ARRAY_SIZE(baud_list); ++i) {
		idx = f81534_find_clk(baud_list[i]);
		if (idx >= 0) {
		baudrate = baud_list[i];
		if (baudrate == 0) {
		tty_encode_baud_rate(tty, 0, 0);
		return 0;
		}

		idx = f81534_find_clk(baudrate);
		if (idx >= 0) {
		tty_encode_baud_rate(tty, baudrate, baudrate);
		break;
		}