Allow ARG_MAX execve string space even with a small stack limit
Allow ARG_MAX execve string space even with a small stack limit

The new code that removed the limitation on the execve string size
(which was historically 32 pages) replaced it with a much softer limit
based on RLIMIT_STACK which is usually much larger than the traditional
limit.  See commit b6a2fea39318e43fee84fa7b0b90d68bed92d2ba ("mm:
variable length argument support") for details.

However, if you have a small stack limit (perhaps because you need lots
of stacks in a threaded environment), the new heuristic of allowing up
to 1/4th of RLIMIT_STACK to be used for argument and environment strings
could actually be smaller than the old limit.

So just say that it's ok to have up to ARG_MAX strings regardless of the
value of RLIMIT_STACK, and check the rlimit only when going over that
traditional limit.

(Of course, if you actually have a *really* small stack limit, the whole
stack itself will be limited before you hit ARG_MAX, but that has always
been true and is clearly the right behaviour anyway).

Acked-by: Carlos O'Donell <ab5e2bca84933118bbc9d48ffaccce3bac4eeb64@codesourcery.com>
Cc: Michael Kerrisk <0cfecf71a00d0f7f793e93dfe880eea69cf034a2@googlemail.com>
Cc: Peter Zijlstra <645ca7d3a8d3d4f60557176cd361ea8351edc32b@chello.nl>
Cc: Ollie Wild <1f67c1db026e2d0c287fd634de9ae682689e622f@google.com>
Signed-off-by: Linus Torvalds <69652caca27c8b940640ad396ab71f93cacec34f@linux-foundation.org>

TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs