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[Bugfix][Parser] GLM-4.7: stray arg tags must not leak into tool-call argument keys - #54971
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Manny7717
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Verified locally on head 7fec1f39 vs base 41848ca — fix is correct and regression-proven.
Bug confirmed on base: both stray-tag shapes reproduce the reported leak exactly. _ARG_KEY replaced .*? (which backtracks across its own </arg_key> delimiter to reach a following <arg_value>) with a possessive non-<-crossing key group:
<arg_key>path</arg_key></arg_key><arg_value>/tmp/x</arg_value>→ base produced keypath</arg_key>(the exact production failure in the PR body); head →{"path": "/tmp/x"}.<arg_key><arg_key>path</arg_key><arg_value>...→ base produced key<arg_key>path; head correct.
Regression-proven: all 5 new tests FAIL on base (4 param converter tests + the streaming e2e test), PASS on head. Full file: 20/20 pass on head vs 5 failed/15 passed on base (teardown RuntimeError: Cannot access accelerator device errors are the known CUDA-less noise, identical on both).
No regressions on adjacent shapes — probed base-vs-head over 22 inputs: well-formed single/multi-arg, \s* whitespace variants, keys containing < (e.g. a<b), arg_key-like markup inside values, empty keys/values, newlines, trailing partial values, junk prefix. Byte-identical output everywhere except the corrupt-key cases. One deliberate delta on the malformed two-keys-one-value input: base merged a</arg_key><arg_key>b into one corrupt key; head drops the value-less a and keeps {"b": "1"} — cleaner fail behavior, not a regression.
Non-blocking note: vllm/tool_parsers/poolside_v1_tool_parser.py:82 uses the same <arg_key>(.*?)</arg_key>\s*<arg_value>(.*?)</arg_value> shape with stdlib re — same leak exists there (findall on <arg_key>path</arg_key></arg_key><arg_value>/tmp/x</arg_value> returns [('path</arg_key>', '/tmp/x')]). If poolside models can emit stray arg tags too, the same [^<]*+(?:<(?!/?arg_key>)[^<]*+)*+ key pattern would apply. Out of scope for this PR, just flagging the sibling.
Nice work — clear root-cause writeup, the _ARG_KEY comment explains the backtracking subtlety precisely, and the streaming e2e test is exactly the right level to prove the engine path.
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Thanks for the catch, @Manny7717 — |
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This pull request has merge conflicts that must be resolved before it can be |
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… argument keys
`_glm47_arg_converter` matched the argument key with an unbounded `.*?`
before `</arg_key>`. Because the group is non-greedy but unbounded, the
regex engine backtracks *past* the first `</arg_key>` whenever that is
what it takes to reach the following `<arg_value>` -- so a repeated or
stray tag in the model stream is absorbed into the key rather than
ignored.
Observed in production against a GLM server run with
`--tool-call-parser glm47`: an argument object came back as
`{"path</arg_key>": "/Users/user/Desktop/project"}`. The client rejected
the call ("must have required property 'path'"), and the model then
retried with an invented path.
Match runs of non-`<` text instead, so the key group cannot cross its own
delimiter, and accept a run of closing tags so the intended key survives.
Well-formed input is unaffected. The unrolled possessive form also avoids
the backtracking a tempered dot would add on the streaming path, which
re-runs the converter over the whole accumulated buffer on every chunk:
on an unterminated 20 KB buffer it is 1251 us -> 10 us.
Covers both `_ARG_RE` and `_PARTIAL_ARG_RE`, with a streaming test that
fails if only one of the two is fixed.
Signed-off-by: pctablet505 <55033230+pctablet505@users.noreply.github.com>
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…-call argument keys
PoolsideV1ToolParser.func_arg_regex captures the argument key with a plain
`.*?`:
r"<arg_key>(.*?)</arg_key>\s*<arg_value>(.*?)</arg_value>"
A non-greedy `.*?` only guarantees the *shortest match starting from the
left*, not that it stops at the first literal occurrence of `</arg_key>`
once the rest of the pattern is considered: if matching `\s*<arg_value>`
fails right after the first `</arg_key>`, the engine backtracks and lets
`.*?` cross that boundary to reach a later one, absorbing a stray
`<arg_key>`/`</arg_key>` tag into the key. Same defect class, same fix
shape, as the GLM-4.7 leak fixed in vllm-project#54971: bound the key to runs of
non-`<` text so the capture cannot cross its own delimiter.
r"<arg_key>([^<]*+(?:<(?!/?arg_key>)[^<]*+)*+)(?:</arg_key>\s*)+"
r"<arg_value>(.*?)</arg_value>"
Not a duplicate of vllm-project#54678, which fixes catastrophic backtracking (a timing
defect) in this file's `func_detail_regex` and adds a regex-timeout guard
around all three patterns in `extract_tool_calls`, including this one's
`.findall` call site -- but it leaves `func_arg_regex`'s pattern itself
unchanged, so the key-leak this PR fixes is still present after vllm-project#54678.
Signed-off-by: pctablet505 <55033230+pctablet505@users.noreply.github.com>
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Signed-off-by: pctablet505 <55033230+pctablet505@users.noreply.github.com>
Keep the one comment a reader needs; the bug narrative lives in the PR description. Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com> Signed-off-by: pctablet505 <55033230+pctablet505@users.noreply.github.com>
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Brought this branch up to date with
I also trimmed the bug-narrative comments and test docstrings down to what a reader needs (the explanation stays in the description), and refreshed the related-PR list (#60842 and #58418 are new neighbours; neither changes the key pattern). @sfeng33, you last touched |
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Synced this branch with latest |
Signed-off-by: pctablet505 <55033230+pctablet505@users.noreply.github.com>
Overview
With
--tool-call-parser glm47, a duplicated<arg_key>or</arg_key>tag in the model output ends up inside the argument name. Seen in production as{"path</arg_key>": "/Users/user/Desktop/project"}, which the client rejects withmust have required property 'path'. The key pattern is now bounded so it cannot cross anarg_keytag, in both the complete-call and the streaming regex.Sibling fix for the Poolside parser: #56093.
Claims
arg_keytags no longer reach the key, for complete calls (_ARG_RE) and streaming (_PARTIAL_ARG_RE).Validation
CPU only (macOS, Python 3.12, torch 2.14.1). Run on 2026-10-14 against
eca1f5743(mainat7115b70c0, includes #61253). The commits after it only mergemain.glm47_moe.pytaken frompytest tests/tool_parsers/test_glm47_moe_tool_parser.pymain_PARTIAL_ARG_RErevertedNew tests:
test_arg_converter_ignores_stray_arg_tagsandtest_partial_arg_converter_ignores_stray_arg_tagscover a repeated closing tag, a repeated opening tag, and a well-formed control. The first goes through_ARG_RE; the second leaves out</arg_value>, so it goes through_PARTIAL_ARG_RE.TestGlm47Streaming::test_stray_arg_key_tagruns end to end throughextract_tool_calls_streaming.The 5 failures on
mainare the four malformed converter cases plus the streaming test. The last row shows that the streaming half is tested separately.Also:
tests/reasoning/test_glm4_moe_reasoning_parser.py,tests/tool_parsers/test_glm4_moe_tool_parser.py,tests/parser/engine/test_glm47_moe.py): 46 passed.ruff checkandruff format --checkpass on the changed files.mainwith this branch on 22 inputs: whitespace variants, keys containing<, tag-like text inside values, empty keys or values, and partial values. Output was identical except for the corrupt-key cases.Local-only workaround: vLLM's autouse teardown calls
torch.accelerator.empty_host_cache(), which segfaults on CPU-only macOS torch. For these runs it was stubbed out with a local pytest plugin. Nothing in the repo was changed for this.Details
Root cause. Both regexes matched the key with
(?P<key>.*?)</arg_key>\s*<arg_value>. The lazy.*?still runs past the first</arg_key>when the next text is not<arg_value>, so a duplicated closing tag gets absorbed into the key. With a duplicated opening tag, the match simply starts at the first<arg_key>.main<arg_key>path</arg_key></arg_key><arg_value>/tmp/x</arg_value>{"path</arg_key>": "/tmp/x"}{"path": "/tmp/x"}<arg_key><arg_key>path</arg_key><arg_value>/tmp/x</arg_value>{"<arg_key>path": "/tmp/x"}{"path": "/tmp/x"}Fix. Both regexes now share one key pattern:
<, but not anarg_keytag, so it stops at the first</arg_key>. Then(?:</arg_key>\s*)+consumes any duplicated closing tags.<arg_key>a</arg_key><arg_key>b</arg_key><arg_value>1</arg_value>) used to produce a single corrupt key,a</arg_key><arg_key>b. It now produces{"b": "1"}.Overlapping PRs.
_glm47_parse_args, which still uses_ARG_RE/_PARTIAL_ARG_RE. Its author also tested it with these patterns applied.AI assistance: used for this change. I reviewed every changed line and ran the tests above.
Pull Request Checklist
I used vLLM's
/pr-checklistskill. (Mandatory for agents, optional for humans).AI assistance was used during the creation of this PR.
Design Fit: Minimizes impact on core components, reuses existing functionality, and justifies added complexity.
Testing and Validation: Validates the change and ensures any added tests are meaningful and reliable, with CI coverage or documented CI resource constraints and validation performed outside CI.
Code Quality and Style: Keeps code and comments clear and concise, and updates relevant documentation and examples.
Pull Request Contents: Includes a brief summary and relevant links, supports claims with evidence, explains root causes and implementation trade-offs, and follows the contributing guide.