[Issue 3342] New: TLS on dynamically loaded DLLs fails on Windows earlier than Vista

Sep 25, 2009

Walter Bright

Oct 26, 2009

Don

Mar 06, 2010

Mar 10, 2010

Mar 10, 2010

Apr 10, 2010

http://d.puremagic.com/issues/show_bug.cgi?id=3342 Summary: TLS on dynamically loaded DLLs fails on Windows earlier than Vista Product: D Version: 2.034 Platform: Other URL: http://www.nynaeve.net/?p=187 OS/Version: Windows Status: NEW Severity: normal Priority: P2 Component: DMD AssignedTo: nobody@puremagic.com ReportedBy: bugzilla@digitalmars.com --- Comment #0 from Walter Bright <bugzilla@digitalmars.com> 2009-09-24 23:02:40 PDT --- A full description of the problem: http://www.nynaeve.net/?p=187 The symptom of the problem is erratic memory corruption. The only known workaround at the moment is to not use TLS on dynamically loaded DLLs for machines running Windows XP or earlier. Use __gshared instead. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=3342 Don <clugdbug@yahoo.com.au> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |clugdbug@yahoo.com.au Severity|normal |blocker --- Comment #1 from Don <clugdbug@yahoo.com.au> 2009-10-26 02:18:58 PDT --- Marking as blocker, since this prevents me from using D2 professionally. It's currently not possible to avoid using TLS (even if you completely avoid Phobos), since druntime uses it. Note that this problem only applies to _implicit_ TLS. Explicit TLS, using TlsGetValue() and TlsSetValue(), still works. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=3342 Rainer Schuetze <r.sagitario@gmx.de> changed: What |Removed |Added ---------------------------------------------------------------------------- CC| |r.sagitario@gmx.de --- Comment #2 from Rainer Schuetze <r.sagitario@gmx.de> 2010-03-06 08:42:18 PST --- I've posted a patch for multi-threading support for DLLs here in bug #3885. This includes a fix for implicite TLS on XP. It needs to access some global data in ntdll.dll, and the way to get there is not really obvious, but seems to be valid for all the ntdll-versions I have found on my system: SP2, one inbetween and SP3. -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

http://d.puremagic.com/issues/show_bug.cgi?id=3342 --- Comment #3 from Walter Bright <bugzilla@digitalmars.com> 2010-03-09 23:11:09 PST --- I've been looking at the patch, it's an impressive piece of work! But I'd like it to detect the Windows version, and not do anything if it is Vista or newer, as those systems don't have the TLS bug. If we don't do this check, since the patch relies on undocumented ntdll internals, D apps are vulnerable to breaking with Windows updates. Also, skywing has some code to deal with this at http://www.nynaeve.net/Code/VistaImplicitTls.cpp Can you check it to see if anything was missed? Thanks! -- Configure issuemail: http://d.puremagic.com/issues/userprefs.cgi?tab=email ------- You are receiving this mail because: -------

March 10, 2010

[Issue 3342] TLS on dynamically loaded DLLs fails on Windows earlier than Vista

Posted by Rainer Schuetze
in reply to Walter Bright

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Rainer Schuetze

Posted in reply to Walter Bright

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http://d.puremagic.com/issues/show_bug.cgi?id=3342



--- Comment #4 from Rainer Schuetze <r.sagitario@gmx.de> 2010-03-10 01:32:28 PST ---
There is a detection whether _tls_index is set and the tls-data-array contains a valid pointer (thinking about it the latter might be flawed), so this should cover any situation where the OS did not setup TLS correctly (when loaded at process init time, TLS is correct on XP, too).

Do you think, that an explicite version check is better? What about applications that are configured to pretend running under a different windows version?

As much as I can see, the referenced code contains two things not in the patch:

- it keeps track of used tls-indexes in a bitmap, but XP does not have this.
That's why the patch prevents unloading of the DLL.
- it uses ExReleaseRundownProtection before accessing some TEB data, but this
seems to be an (undocumented) kernel function, and I think we should be safe
with our operations as the nt-loader holds a lock that disallows reentrence
into DllMain

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