ims_registrar_pcscf: Update tmp security only if there are sec-agree …

[tdimitrov]

…params in the message

Pre-Submission Checklist

• [ X] Commit message has the format required by CONTRIBUTING guide
• [ X] Commits are split per component (core, individual modules, libs, utils, ...)
• [ X] Each component has a single commit (if not, squash them into one commit)
• [ X] No commits to README files for modules (changes must be done to docbook files
  in doc/ subfolder, the README file is autogenerated)

Type Of Change

• [X ] Small bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds new functionality)
• Breaking change (fix or feature that would change existing functionality)

Checklist:

• [X ] PR should be backported to stable branches
• [X ] Tested changes locally
• [X ] Related to issue P-CSCF crash during client login #1526

Description

If a register is received without sec-agree parameters, a NULL pointer is deferenced, which causes segfault.

[uts09]

Thanks a lot @tdimitrov!

[tdimitrov]

You are welcome @uts09 . Thank you for reporting this.