[openssl-users] Openssl static build linked in DLL does not unload on win32

[Ryan Murray]

Do you have a moment to edit or review my error

Ryan Murray

On Jan 6, 2017 10:55 AM, "Matt Caswell" <matt at openssl.org> wrote:

>
>
> On 06/01/17 14:36, Dan Heinz wrote:
> >>> On 04/01/17 23:11, Dan Heinz wrote: Using openssl 1.1.0c.
> >>>
> >>> I have a test application that is a win32 console app that calls
> >>> a win32 DLL which has the openssl libraries linked in
> >>> statically.
> >>>
> >>> The test applications uses late-binding to the DLL and calls
> >>> LoadLibrary for the DLL, one test function in the DLL, and then
> >>> FreeLibrary on the DLL.
> >>>
> >>>
> >>>
> >>> The test function in the DLL does the following:
> >>>
> >>> RSA*rsa = NULL;
> >>>
> >>> rsa = RSA_new();
> >>>
> >>> RSA_free(rsa);
> >>>
> >>> OPENSSL_thread_stop();
> >>>
> >>> OPENSSL_cleanup();
> >>>
> >>> return0;
> >>>
> >>> When FreeLibrary is called on the DLL, dllmain in never called
> >>> with any messages.  A subsequent call to LoadLibrary also fails
> >>> to call dllmain and when the test function is called RSA_new()
> >>> fails.  This leads me to believe the DLL is never freed.
> >>>
> >>> I have tried building openssl with and without no-threads with
> >>> the same results.  My build parameters are: perl Configure
> >>> *%TEMP_ARCHITECTURE%*
> >>> --prefix=*%RootPath_ThirdParty%*\*%OPENSSL_VERSION%* -DPURIFY
> >>> -DOPENSSL_NO_COMP -D_USING_V110_SDK71_ no-shared no-threads
> >>> no-asm no-idea no-mdc2 no-rc5  no-ssl3 no-zlib no-comp
> >>>
> >>> What am I missing?
> >>
> >>
> >> OpenSSL does its cleanup at *process* exit. Don't call
> >> OPENSSL_cleanup() explicitly - this is >discouraged.
> >>
> >> From this manpage:
> >>
> >> https://www.openssl.org/docs/man1.1.0/crypto/OPENSSL_init_crypto.html
> >>
> >>
> >>
> "Typically there should be no need to call this function directly as it
> is initiated >automatically on application exit...<snip>...
> >>
> >> Once OPENSSL_cleanup() has been called the library cannot be
> >> reinitialised."
> >>
> >> This last sentence is the reason why RSA_new() will fail after you
> >> have previously called >OPENSSL_cleanup().
> >>
> >> Because cleanup happens on process exit, OpenSSL will keep itself
> >> in memory until that time >(otherwise crashes will occur because
> >> the cleanup routines have been unloaded).
> >>
> >> If you want to dynamically load and unload your DLL then don't
> >> statically link it to OpenSSL - >otherwise OpenSSL will keep your
> >> DLL around until process exit too.
> >>
> >> Matt
> >
> > That is very disappointing.  As a library vendor we have no control
> > over how our users load and unload our libraries.  We will just have
> > to roll back to 1.0.x and wait to see if this will be addressed.
> > Also, as Jakob stated in another post, it really seems like this
> > design will be problematic.
>
> Can you not link against the OpenSSL DLLs rather than statically link?
> That would avoid the problem.
>
> Matt
>
>
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