fix: crash when parsing heredocs with identifiers >= 256 chars#287
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look wants to merge 1 commit intotree-sitter:masterfrom
Open
fix: crash when parsing heredocs with identifiers >= 256 chars#287look wants to merge 1 commit intotree-sitter:masterfrom
look wants to merge 1 commit intotree-sitter:masterfrom
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The heredoc word length was serialized as a single byte, which silently truncated identifiers of >= 256 characters. The deserializer would then read the wrong length, leaving unread bytes in the buffer, and hit the assert(size == length) check.
look
commented
Feb 10, 2026
| for (uint32_t i = 0; i < scanner->open_heredocs.size; i++) { | ||
| Heredoc *heredoc = array_get(&scanner->open_heredocs, i); | ||
| if (size + 2 + heredoc->word.size >= TREE_SITTER_SERIALIZATION_BUFFER_SIZE) { | ||
| if (size + 3 + sizeof(uint32_t) + heredoc->word.size >= TREE_SITTER_SERIALIZATION_BUFFER_SIZE) { |
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I believe 2 is incorrect in the old code: we write 3 bools below, not 2.
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I identified a crash in GitHub's symbol extraction system related to tree-sitter-ruby. Investigation revealed it was caused by very long HEREDOC identifiers (these are legal in Ruby, I checked...).
The heredoc word length was serialized as a single byte, which silently truncated identifiers of >= 256 characters. The deserializer would then read the wrong length, leaving unread bytes in the buffer, and hit the
assert(size == length)check.To fix, I adopted the approach used in tree-sitter-bash and tree-sitter-php: store the HEREDOC identifier length in a
uint32_t.This PR includes a reproduction test. If you run
tree-sitter testonmasterwithtest/corpus/literals.txtyou will get:On this branch, it is fixed.
Disclaimer: I used GitHub Copilot to help diagnose and fix this bug.