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Date: Wed, 8 Nov 2017 11:05:46 +0800 From: "Ji-Ze Hong (Peter Hong)" <hpeter@...il.com> To: gregkh@...uxfoundation.org Cc: jslaby@...e.com, lukas@...ner.de, rel+kernel@...lox.net, linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org, ricardo.ribalda@...il.com, "Ji-Ze Hong (Peter Hong)" <hpeter+linux_kernel@...il.com> Subject: [PATCH V1 1/1] serial: 8250_fintek: Fix crash with baud rate B0 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: 195638b6d44f ("serial: 8250_fintek: UART dynamic clocksource on Fintek F81866") Reported-by: Lukas Redlinger <rel+kernel@...lox.net> Cc: Lukas Redlinger <rel+kernel@...lox.net> Signed-off-by: Ji-Ze Hong (Peter Hong) <hpeter+linux_kernel@...il.com> --- drivers/tty/serial/8250/8250_fintek.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/8250/8250_fintek.c b/drivers/tty/serial/8250/8250_fintek.c index c41cbb52f1fe..3d66c2c0d7ee 100644 --- a/drivers/tty/serial/8250/8250_fintek.c +++ b/drivers/tty/serial/8250/8250_fintek.c @@ -312,6 +312,13 @@ 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; @@ -324,8 +331,7 @@ 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) { @@ -353,6 +359,7 @@ 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); } -- 2.7.4
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