Re: [PATCH 04/10] proc: fix PAGE_SIZE limit of /proc/$PID/cmdline

[Alexey Dobriyan]

On Thu, Jul 17, 2014 at 03:53:46PM -0700, Andrew Morton wrote:
> On Thu, 17 Jul 2014 00:32:47 +0300 Alexey Dobriyan <adobriyan@xxxxxxxxx> wrote:
> 
> > Convert /proc/$PID/cmdline to seq_file interface.
> > 
> > XXX
> 
> Unsure what XXX signifies.
> 
> > This one must be buggy.
> > 
> > seq_file buffer is adjustable, so userspace can execute itself
> > with huge command line (which can be arbitrarily long now), then read 1 byte.
> > 
> > Voila, whole command line now is in kmalloced/vmalloced memory.
> > 
> > Imposing limit is trivial but equally lame to current PAGE_SIZE limit.
> 
> Confused. Why send the patch if you don't like it?
> 
> Why not go ahead and impose the PAGE_SIZE limit?

I thought someone smarter than me would suggest what to do.

Please replace with v2.
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