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 <[email protected]>
Cc: Lukas Redlinger <[email protected]>
Signed-off-by: Ji-Ze Hong (Peter Hong) <[email protected]>
---
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
From 1583566680357273706@xxx Thu Nov 09 05:54:31 +0000 2017
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