Fix use-after-free violation in NetlinkException

[abeltrano]

Type

• Bug fix
• Feature addition
• Feature update
• Documentation
• Build Infrastructure

Side Effects

• Breaking change
• Non-functional change

Goals

• Fix Bug: NetlinkException causes use-after-free violation #294
• Ensure throwing a NetlinkException does not cause a crash or weird results when later reading the error category information from the NetlinkException instance.

Technical Details

When creating an instance of NetlinkException, and temporary instance of NetlinkErrorCategory is passed to the std::error_code constructor. However, std::error_code expects a const reference and does not make a copy of it. Since we passed a temporary, this later results in a use-after-free bug which would cause either a crash (good case) or weird results when reading the error category information from the NetlinkException later. This is solved by using a singleton NetlinkErrorCategory and passing this instance to the std::error_code constructor.

• Add function to generate singleton instance of NetlinkErrorCategory.
• Pass valid, long-lived instance of NetlinkErrorCategory to std:;error_code constructor when creating a NetlinkException.
• Add unit test to ensure NetlinkException doesn't cause a crash or trigger AddressSanitizer.

Test Results

• All unit tests pass.

Reviewer Focus

• None

Future Work

• None

Checklist

• Build target all compiles cleanly.
• clang-format and clang-tidy deltas produced no new output.
• Newly added functions include doxygen-style comment block.