Re: [PATCH 3.19 3/3] x86, mpx: Change the MPX enable/disable API to arch_prctl

[Dave Hansen]

On 01/05/2015 03:04 PM, Andy Lutomirski wrote:
> Anyway, if it's actually a problem to change it, I have no real
> problem keeping it, but I think we *really* need to validate the rest
> of the arguments at the very least.

If we "validate" the arguments like you suggested, then a call like this:

	prctl(PR_MPX_DISABLE_MANAGEMENT);

ends up returning -EINVAL:

> prctl(0x2b /* PR_??? */, 0x7fffffd3, 0x7f360955e9e0, 0x2c, 0x7f3609314840) = -1 EINVAL (Invalid argument)

A quick grep through ltp and some other source I have laying around does
*not* show folks adding 0's to these calls for "empty" arguments.  Is
this really something we want to do?

	prctl(PR_MPX_DISABLE_MANAGEMENT, 0, 0, 0, 0);
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