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 the 3.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
serial-fix-divide-by-zero-fault-in-uart_get_divisor.patch
and it can be found in the queue-3.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>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()
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From: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
commit 547039ec502076e60034eeb79611df3433a99b7d upstream.
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>
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(-)
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -353,7 +353,7 @@ uart_get_baud_rate(struct uart_port *por
* The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
* Die! Die! Die!
*/
- if (baud == 38400)
+ if (try == 0 && baud == 38400)
baud = altbaud;
/*
Patches currently in stable-queue which might be from peter@xxxxxxxxxxxxxxxxxx are
queue-3.14/serial-fix-divide-by-zero-fault-in-uart_get_divisor.patch
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