[tbb-bugs] #22584 [Applications/Tor Browser]: More RWX memory pages for TBB on some Windows versions

Tor Bug Tracker & Wiki blackhole at torproject.org
Fri Jun 16 09:10:17 UTC 2017

#22584: More RWX memory pages for TBB on some Windows versions
 Reporter:  arthuredelstein           |          Owner:  tbb-team
     Type:  defect                    |         Status:  new
 Priority:  Medium                    |      Milestone:
Component:  Applications/Tor Browser  |        Version:
 Severity:  Normal                    |     Resolution:
 Keywords:  tbb-security              |  Actual Points:
Parent ID:                            |         Points:
 Reviewer:                            |        Sponsor:

Comment (by arthuredelstein):

 Replying to [comment:4 cypherpunks]:
 > ticket:21617#comment:14 is about `softokn3.dll` and `freebl3.dll` have
 `W^X` pages on Windows 10 (15063) for unknown reason.
 > `about:support` page is a good way to force lazyloaders in Firefox to
 load DLLs.

 I'm able to reproduce the RWX pages for these two DLLs. They are all
 labeled ".text", which leads me to assembly code in the freebl and
 softoken parts of the mozilla codebase. But I don't see anything
 explicitly requesting RWX or X/COW memory.

 Interestingly, I don't see these RWX pages in the latest release version
 of Firefox. And, if I build tor-browser.git using `./mach build` on
 Windows, I also don't see any RWX pages. That suggests to me that the RWX
 pages observed in TBB may be related to how we are building tor-
 browser.git with mingw32-gcc.

Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22584#comment:7>
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