|Summary:||linprocfs: Chromium requires /proc/self/task implementation|
|Product:||Base System||Reporter:||Alex S <iwtcex>|
|Component:||kern||Assignee:||Edward Tomasz Napierala <trasz>|
|Severity:||Affects Only Me||CC:||trasz|
|Bug Depends on:|
Description Alex S 2019-10-02 01:01:18 UTC
Otherwise you'll get a nice crash at the corresponding assertion checks, see https://cs.chromium.org/chromium/src/sandbox/linux/services/thread_helpers.cc?l=41&rcl=90c6c958243e775074d81e19c204f196d8e76990 and https://cs.chromium.org/chromium/src/sandbox/linux/services/thread_helpers.cc?l=44&rcl=90c6c958243e775074d81e19c204f196d8e76990. (Actually, not so nice crash, for some reason most Chromium assertion checks do not produce any error messages whatsoever.)
Comment 1 Edward Tomasz Napierala 2020-01-13 12:24:04 UTC
I've glanced at this, and it seems somewhat non-trivial. The problem here is that pseudofs(5), which is what linprocfs(5) uses underneath, does not support nested PFS_PROCDEP directories; they trigger a KASSERT, and if you remove that, you'll get a nested lock attempt.
Comment 2 Conrad Meyer 2020-03-23 23:37:24 UTC
It seems these routines are used only to implement other assertion/CHECKs (most uses are in thread_helpers_unittests.cc and the only external uses seem to be in credentials.cc and scoped_process.cc, both inside CHECK()), and since we mostly build Chrome in Release mode, we don't hit these. A more straightforward fix for debug mode is to patch Chrome rather than procfs.
Comment 3 Alex S 2020-03-24 07:21:38 UTC
(In reply to Conrad Meyer from comment #2) All assertions are enabled in release builds. I should have provided a bit more context. This issue is about Linux executables running on Linuxulator. My personal use case is the Linux Steam client, but I expect this to be a bit more broadly useful. Say, for Widevine or whatever proprietary crap. Indeed, those checks are not particularly important. To get around them I'm using an LD_PRELOADable hack  with a couple of stubs and CEF (Chromium Embedded Framework) doesn't seem to care. The hack was tested with debug CEF builds , Steam's embedded browser and one Feral Interactive's game launcher ("conveniently" built into a single executable with the game). : https://github.com/shkhln/linuxulator-steam-utils/blob/3239b35d78d25cf821fd906fddd25ff34ecc84a2/src/webfix.c#L67 : sample application @ http://opensource.spotify.com/cefbuilds/index.html
Comment 4 Alex S 2020-03-24 07:26:15 UTC
Wtf with this bug tracker always sending an email to some guy at @intel? Are we deliberately spamming them?
Comment 5 Alex S 2020-04-03 01:24:07 UTC
(In reply to Alex S from comment #3) > whatever proprietary crap A case in point: https://lists.freebsd.org/pipermail/freebsd-emulation/2020-March/017800.html.
Comment 6 commit-hook 2020-06-30 16:25:08 UTC
A commit references this bug: Author: trasz Date: Tue Jun 30 16:24:28 UTC 2020 New revision: 362806 URL: https://svnweb.freebsd.org/changeset/base/362806 Log: Make linprocfs(5) create the /proc/<PID>/task/ directores. This is to silence down some Chromium assertions. PR: kern/240991 Analyzed by: Alex S <email@example.com> MFC after: 2 weeks Sponsored by: The FreeBSD Foundation Differential Revision: https://reviews.freebsd.org/D25256 Changes: head/sys/compat/linprocfs/linprocfs.c
Comment 7 commit-hook 2020-08-13 18:54:59 UTC
A commit references this bug: Author: trasz Date: Thu Aug 13 18:54:02 UTC 2020 New revision: 364209 URL: https://svnweb.freebsd.org/changeset/base/364209 Log: MFC r362806: Make linprocfs(5) create the /proc/<PID>/task/ directores. This is to silence down some Chromium assertions. PR: kern/240991 Analyzed by: Alex S <firstname.lastname@example.org> Sponsored by: The FreeBSD Foundation Changes: _U stable/12/ stable/12/sys/compat/linprocfs/linprocfs.c