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serial: 8250_fintek: Fix crash with baud rate B0

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The 8250_fintek.c is support the Fintek F81866/F81216 with dynamic clock.
But It'll generate "division by zero" exception and crash in
fintek_8250_set_termios() with baud rate 0 on baudrate_table[i] % baud.

It can be tested with following C code:

	...
	struct termios options;

	tcgetattr(fd, &options);
	...
	options.c_cflag = CS8 | CREAD; /* baud rate 0 */
	tcsetattr(fd, TCSANOW, &options);
	tcflush(fd, TCIOFLUSH);

Fixes: 195638b6d4 ("serial: 8250_fintek: UART dynamic clocksource on Fintek F81866")
Reported-by: Lukas Redlinger <rel+kernel@agilox.net>
Cc: Lukas Redlinger <rel+kernel@agilox.net>
Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ji-Ze Hong (Peter Hong) 2017-11-08 11:05:46 +08:00 committed by Greg Kroah-Hartman
parent 21c4e7f255
commit 07a708f0a1
1 changed files with 9 additions and 2 deletions
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11
drivers/tty/serial/8250/8250_fintek.c
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@ -315,6 +315,13 @@ void fintek_8250_set_termios(struct uart_port *port, struct ktermios *termios,
F81866_UART_CLK_14_769MHZ, F81866_UART_CLK_18_432MHZ,
F81866_UART_CLK_24MHZ };
/*
* We'll use serial8250_do_set_termios() for baud = 0, otherwise It'll
* crash on baudrate_table[i] % baud with "division by zero".
*/
if (!baud)
goto exit;
switch (pdata->pid) {
case CHIP_ID_F81216H:
reg = RS485;
@ -327,8 +334,7 @@ void fintek_8250_set_termios(struct uart_port *port, struct ktermios *termios,
dev_warn(port->dev,
"%s: pid: %x Not support. use default set_termios.\n",
__func__, pdata->pid);
serial8250_do_set_termios(port, termios, old);
return;
goto exit;
}
for (i = 0; i < ARRAY_SIZE(baudrate_table); ++i) {
@ -356,6 +362,7 @@ void fintek_8250_set_termios(struct uart_port *port, struct ktermios *termios,
tty_termios_encode_baud_rate(termios, baud, baud);
}
exit:
serial8250_do_set_termios(port, termios, old);
}