This is a note to let you know that I've just added the patch titled
serial: Fix divide-by-zero fault in uart_get_divisor()
to my tty git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/tty.git
in the tty-linus branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.
If you have any questions about this process, please let me know.
>From 547039ec502076e60034eeb79611df3433a99b7d Mon Sep 17 00:00:00 2001
From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Date: Thu, 16 Oct 2014 13:46:38 -0400
Subject: serial: Fix divide-by-zero fault in uart_get_divisor()
MIME-Version: 1.0
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uart_get_baud_rate() will return baud == 0 if the max rate is set
to the "magic" 38400 rate and the SPD_* flags are also specified.
On the first iteration, if the current baud rate is higher than the
max, the baud rate is clamped at the max (which in the degenerate
case is 38400). On the second iteration, the now-"magic" 38400 baud
rate selects the possibly higher alternate baud rate indicated by
the SPD_* flag. Since only two loop iterations are performed, the
loop is exited, a kernel WARNING is generated and a baud rate of
0 is returned.
Reproducible with:
setserial /dev/ttyS0 spd_hi base_baud 38400
Only perform the "magic" 38400 -> SPD_* baud transform on the first
loop iteration, which prevents the degenerate case from recognizing
the clamped baud rate as the "magic" 38400 value.
Reported-by: Robert Święcki <robert@xxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx> # all
Signed-off-by: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/tty/serial/serial_core.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index df3a8c74358e..eaeb9a02c7fe 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -363,7 +363,7 @@ uart_get_baud_rate(struct uart_port *port, struct ktermios *termios,
* The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
* Die! Die! Die!
*/
- if (baud == 38400)
+ if (try == 0 && baud == 38400)
baud = altbaud;
/*
--
2.1.3
--
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