Potential Vulnerability in Cloned Code

[pr-hung]

Summary

This PR fixes a potential security vulnerability in cloned code that appears to have missed an upstream security patch.

Details

• Affected file: Android/AntFluid/markwon-html/src/main/java/io/noties/markwon/html/jsoup/parser/TokeniserState.java
• Affected function: read
• Upstream fix commit: jhy/jsoup@b86beca
• Clone similarity score: 0.9999783635139465

What this PR does

• Applies the upstream security fix logic to the cloned implementation in this repository.

Please review and merge this PR to ensure your repository is protected against this potential vulnerability.
Thank you for your time!

[gemini-code-assist]

Summary of Changes

Hello, 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 addresses a potential security vulnerability by backporting a critical fix from an upstream jsoup library. The change ensures that a pending HTML tag is correctly emitted when the end-of-file is reached during tokenization, preventing potential parsing issues or unexpected behavior that could be exploited.

Highlights

• Security Vulnerability Fix: Applied an upstream security patch to cloned jsoup parser code to address a potential vulnerability related to un-emitted pending tags at EOF.

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Changelog

• Android/AntFluid/markwon-html/src/main/java/io/noties/markwon/html/jsoup/parser/TokeniserState.java
  • Applied an upstream security fix to correctly emit pending tags at the end of the input stream.

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[gemini-code-assist]

Code Review

This pull request applies an upstream security fix from the jsoup library, modifying the tokeniser's behavior at the end of a file (EOF) to ensure pending tags are emitted. This addresses a security vulnerability where an unterminated tag at EOF in the TagName state was not emitted, which could lead to parsing inconsistencies and bypass HTML sanitizers. However, the current fix is incomplete as it only addresses the TagName state. It is recommended to extend this fix to other relevant TokeniserState enum states that handle tag attributes to ensure consistent and secure parser behavior.

[gemini-code-assist]

The fix for the missing tag emission on EOF is incomplete. While this PR correctly adds t.emitTagPending() to the TagName state, several other states in the same file that are involved in building a tag also handle EOF without emitting the pending tag. This inconsistency can lead to tags being dropped if the input ends prematurely, which can be exploited to bypass HTML sanitizers that rely on this parser for security filtering.

The following states are also missing the t.emitTagPending() call in their eof case:

• BeforeAttributeName (line 574)
• AttributeName (line 623)
• AfterAttributeName (line 664)
• AttributeValue_doubleQuoted (line 756)
• AttributeValue_singleQuoted (line 789)
• AttributeValue_unquoted (line 828)
• AfterAttributeValue_quoted (line 865)
• SelfClosingStartTag (line 886)

Interestingly, BeforeAttributeValue (line 709) already correctly handles this. To ensure full protection against this vulnerability, the same fix should be applied to all the states listed above.