[9fans] problem with rminnich's 9vx

[rminnich@gmail.com (ron minnich)]

On Tue, Mar 29, 2011 at 12:05 PM, erik quanstrom
<quanstro at labs.coraid.com> wrote:
> On Tue Mar 29 12:48:21 EDT 2011, forsyth at terzarima.net wrote:
>> in fact, even 64k might be too big a value for the given buf if it's near the
>> top of memory (eg, a local variable on a stack that's in high memory);
>> the PowerPC reference in the original comment is misleading because that
>> was just a particular system where the general problem appeared.
>
> if that's the case, isn't this already a bug. ?the stack doesn't go past
> the end of memory, so how could sprint(buf, "x") not overwrite junk
> past the end of the stack anyway?
>
> also, since this is the kernel, you either get a 4k or a 4k - sizeof(Mach)
> structure (depending on if up is set or not), so the maximum sprint
> to something on the stack is always going to be < 4k.

This discussion is why I did not want to apply that patch, even though
it helps. I just want to make sure I understand the issues and was not
convinced I did.

ron