Messages in this thread | | | Subject | Re: 8250 serial console fixes -- issue | From | Krzysztof Halasa <> | Date | Fri, 03 Feb 2006 18:46:24 +0100 |
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Russell King <rmk+lkml@arm.linux.org.uk> writes:
> My point stands - if the user can provide an arbitary string to printk, > they can fake any kernel message. That in itself is a security bug. > If there is an instance of that, then that's the real bug which would > need fixing.
I think the AT problem is valid - the user doesn't have to be able to send anything to the console, the system alone can screw it up with something as simple as ATZ^M (or with almost any string with embedded [aA][tT].*^M).
_If_ we want to be able to connect a serial console to dial-up modem we can't send _anything_ to it when DCD is down (except configuration strings etc). I don't know exact timings but the modem will probably accept commands hundreds of milliseconds after dropping DCD.
There are/were modems which could be configured using a jumper to password-protected power-on dial-in mode and which doesn't accept further Hayes commands - those are safe (they don't even abort inbound connection negotiation if they receive characters from the computer). -- Krzysztof Halasa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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