fix: mem leak and heap use after free in mnd.

[xiao-77]

Description

Issue(s)

feishu project: 6635875679

• Close/close/Fix/fix/Resolve/resolve: Issue Link

Checklist

Please check the items in the checklist if applicable.

• Is the user manual updated?
• Are the test cases passed and automated?
• Is there no significant decrease in test coverage?

[gemini-code-assist]

Summary of Changes

Hello @xiao-77, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request focuses on enhancing the stability and reliability of the mnd module by resolving critical memory management issues. The changes specifically target and eliminate potential heap use-after-free conditions and memory leaks, which could arise from improper sequencing of resource deallocation. By refining the error handling and cleanup procedures, the PR ensures that system resources are managed correctly, preventing crashes and improving overall system health.

Highlights

• Memory Safety Fix: Addressed potential heap use-after-free vulnerabilities and memory leaks within the mnd module by removing redundant sdbCancelFetch calls in error handling paths.
• Error Handling Refinement: Improved the robustness of error handling logic across several mnd functions by ensuring proper resource release without attempting to cancel fetches on potentially invalid or already freed iterators.
• Code Cleanup: Streamlined cleanup routines in mndShow.h, mndMnode.c, mndRetention.c, and mndVgroup.c by removing unnecessary sdbCancelFetch calls that could lead to undefined behavior.

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[gemini-code-assist]

Code Review

This pull request removes redundant calls to sdbCancelFetch from error handling paths in mndShow.h, mndMnode.c, mndRetention.c, and mndVgroup.c. Specifically, these calls were removed when colDataSetVal or tNameFromString operations failed, streamlining the error cleanup process.