Re: [RFC v1] implement SL*B and stack usercopy runtime checks
From: Linus Torvalds
Date: Sun Jul 03 2011 - 14:28:55 EST
That patch is entirely insane. No way in hell will that ever get merged.
copy_to/from_user() is some of the most performance-critical code, and
runs a *lot*, often for fairly small structures (ie 'fstat()' etc).
Adding random ad-hoc tests to it is entirely inappropriate. Doing so
unconditionally is insane.
So NAK, NAK, NAK.
If you seriously clean it up (that at a minimum includes things like
making it configurable using some pretty helper function that just
compiles away for all the normal cases, and not writing out
if (!slab_access_ok(to, n) || !stack_access_ok(to, n))
multiple times, for chrissake) it _might_ be acceptable.
But in its current form it's just total crap. It's exactly the kind of
"crazy security people who don't care about anything BUT security"
crap that I refuse to see.
Some balance and sanity.
Linus
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