Potential to deadlock in OpenSSL, SChannel and SSPI Negotiate connectors
I’ve been improving my pre-release testing system and now run a lock inversion detector as part of my build machine’s build and test cycle for the socket server examples. This lock inversion detector can detect the potential to deadlock without the code ever needing to actually deadlock, so it’s a pretty powerful tool. It has detected a lock inversion in the async connectors used by the OpenSSL, SChannel and SSPI Negotiate libraries. I’ve fixed these problems and there will be a 6.3.2 release next week.
At present I haven’t finished changing all of the build scripts for all of the servers to include the lock inversion detection phase into the test runs and so there may be more issues yet to be discovered.
Note that these lock inversions have not, as far as I know, ever actually caused a deadlock, but the possibility is there if the right timing occurs between concurrent read and write operations.