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SubjectRe: 8250 serial console fixes -- issue

Hi Alan,

The serial console driver has a host of issues

- end of line should be CR LF, not LF CR

- 'r' option for CTS/RTS flow control assumes CTS is
asserted when DSR is not asserted. This is wrong as
lots of modems float control lines when off. No
control signals are defined is DSR is unasserted.

- [SECURITY] 'r' should require DCD to be asserted
before outputing characters. Otherwise we talk to
Hayes modem command mode. This allows a non-root
user to re-program the modem and is a major security
issue is people configure calling line identification
or encryption to restrict use of the serial console.

- 'r' option has insanely slow CTS timeout. So if a
terminal server is inactive the kernel can take
30 minutes to boot as each character write to the
serial console requires a CTS timeout.

All of these have been reported to me multiple times
(I'm maintainer of the Remote-Serial-Console-HOWTO).

I occassionally clean up and repost a patch I wrote years
ago which never gets integrated (although it ships in the
patchset of a number of kernels from supercomputer vendors).
I'm happy to clean it up again if there's a hope of
integration.

See
<http://www.aarnet.edu.au/~gdt/patch/console/serial-console.patch>
for the most recent attempt.

Thanks so much,
Glen

--
Glen Turner Tel: (08) 8303 3936 or +61 8 8303 3936
Australia's Academic & Research Network www.aarnet.edu.au
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