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Android 17 bionic wide-character scans can misidentify non-ASCII text

github.com 7 min read Editor score 7/10

On affected Android 17 builds, wcscspn() and wcspbrk() can treat the first character at or above U+0100 as a match under a specific reject-set condition. The issue shows how a low-level libc bug can break text scanning across emoji and non-Latin scripts.

What: Android 17 September builds have a bionic bug in wcscspn() and wcspbrk() that can misidentify non-ASCII text as a match.
How: With a reject set of at least two characters below U+0100, scans stop at any haystack character at or above U+0100; other listed wide-string functions work correctly.
Why it matters: Wide-character delimiter scans can break on emoji, CJK and other non-ASCII text, so engineers should test such inputs.

The reject set populates a table that wcscspn uses while scanning the haystack. Sketched from the article's own text.

Read on github.com → Hacker News · 242 comments

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