FreeTDS Development Group

[Mitch Freed <mfreed AT nitrosecurity.com>]

I have 2 threads each with their *own* connection to different servers. 
The problem is

static SSL_CTX *ssl_ctx

inside net.c and the way it is being initialized.

- Mitch

On 12/15/2011 06:18 AM, Frediano Ziglio wrote:
> 2011/12/15 Mitch Freed<mfreed AT nitrosecurity.com>:
> > Is ct_connect (libct) not thread-safe? It looks like it's calling
> > tds_init_openssl at some point down the line which calls
> > SSL_library_init. I don't see any checks in place to prevent multiple
> > threads from calling SSL_library_init (tds/net.c) rather than
> > SSL_library_init only being called once by the first thread that sees
> > it's not initialized.
> >
> > I have seen the FAQ indicating that the threads cannot share a
> > CS_CONNECTION, which they do not in my case.
> >
> > I'm getting a SIGABRT with a large stack trace that ends like this:
> >
> > #39 0xf7f3e9f2 in SSL_library_init () from /usr/lib/libssl.so.0.9.8
> > #40 0xf7f421a1 in ?? () from /usr/lib/libssl.so.0.9.8
> > #41 0x0000001d in ?? ()
> > #42 0xf7f3e907 in SSL_library_init () from /usr/lib/libssl.so.0.9.8
> > #43 0xf7f865bb in tds_init_openssl () from /usr/lib/libct.so.4
> > Backtrace stopped: previous frame inner to this frame (corrupt stack?)
> >
> > If I use a mutex in my code around the call to ct_connect I am able to
> > prevent the SIGABRT.
> >
> > Thanks,
> > Mitch
>
> Assuming that 2 threads allocate a ctlib connection and try to open at
> the same time you can have threading problem. In this case
> tds_init_openssl is not threadsafe and should be protected by a mutex.
>
> bye
>    freddy77
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