commonmark / commonmark/cmark

Quadratic output growth with CommonMark renderer

Open
#377 13 comments 0 reactions 0 assignees View on GitHub

Nobody has claimed this yet.

Dominant language
C
Stars
2k
Forks
691
Avg merge
1d 16h
Merged PRs (30d)
1

Description

Found by OSS-Fuzz: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=30784

Reduced test case:

$ printf '>>>>a\nb\nc\nd' |build/src/cmark -t commonmark
> > > > a
> > > > b
> > > > c
> > > > d
$ python3 -c 'print(">"*10000+"a\n"*10000)' |build/src/cmark -t commonmark |wc -c
200020000

Contributor guide

No contributing guide indexed for this repository

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Reproduce the reduced cases with build/src/cmark and the CommonMark renderer, then inspect the renderer path responsible for expanding blockquote prefixes. Confirm the quadratic output behavior and preserve the shown output while eliminating the excessive growth; rerun both commands and compare the byte count.

Written by the indexing model from the issue text.

Assessment

Tech stack
c
Domain
performance
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

Get new issues in your inbox

A short digest of beginner-friendly GitHub issues.