commit 6930df0f1cf6671f356886b068d676a45c3543d6
author Bruce Dawson <brucedawson@chromium.org> Thu Aug 23 00:10:35 2018
committer Commit Bot <commit-bot@chromium.org> Thu Aug 23 18:27:42 2018
tree 93de434a2fbc37c06d870142aee28b95e03421c5
parent adea021bbf90cfc93d032d649f112895a482cb3e

Use PAGE_TARGETS_INVALID when allocating code pages

PAGE_TARGETS_INVALID tells CFG (Control Flow Guard) to mark all
addresses as invalid indirect branch targets. This makes exploits more
difficult. The benefit is minor because most of the code in the Chrome
process doesn't use the CFG checks, but this will close off a few
weaknesses and is the direction we will want to go in eventually
anyway (with specific targets or call sites opted-in to allowing
calls, using SetProcessValidCallTargets).

PAGE_TARGETS_INVALID may ultimately cause CFG to not allocate memory -
that is implied by Windows Internals 7th Edition - and if that is
implemented then this change will save some modest amount of memory.

PAGE_TARGETS_INVALID was introduced in Windows 10 - according to
Windows Internals Part 1 7th Edition - prior to that it will cause
VirtualAlloc to fail.

Bug: chromium:870054
Change-Id: Ib1784fba37cc0ecb5fe5df595f1519531b3b3a20
Reviewed-on: https://chromium-review.googlesource.com/1186025
Commit-Queue: Bruce Dawson <brucedawson@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Reviewed-by: Hannes Payer <hpayer@chromium.org>
Cr-Commit-Position: refs/heads/master@{#55365}