fix(vcs): no project can write into .git or .vcs; hostile input can't crash the host

Radin committed …

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Author

Radin · radin@coline.appOct 28, 2026 at 02:06

Committer

Radin · radin@coline.appOct 28, 2026 at 02:06

Parents

8207c3629fab

fix(vcs): no project can write into .git or .vcs; hostile input can't crash the host

Path safety, as git learned it (CVE-2014-9390 and later):
- A path part can't be .git or .vcs in any spelling a disk treats the
  same (.GIT, .git., git~1, with characters macOS ignores), nor hold a
  backslash. Hosts refuse to land one (Upstream's host, vcs-server, edits,
  imports); importers leave them out; the CLI refuses to write one, never
  picks up a nested .git or .vcs folder, and on Windows refuses names
  Windows can't hold (aux.c, a:b) instead of writing somewhere else.
  Otherwise anyone who can land could plant .git/hooks in others' folders.

Hostile bytes:
- core/tests/hostile.rs mutates valid bundles, trees, chunk lists, git
  packs, deltas, commits and git trees, and makes random ones (about
  40,000 each; VCS_FUZZ_SCALE for more), and requires errors, not panics.
- It found that a git delta's claimed size was allocated as is: a crafted
  push to git main could have crashed the host's isolate. Deltas now
  draw from the pack's budget.
- A compressed object's claimed size isn't trusted either (host and CLI):
  room grows as it's read, reading stops just past it, and the host opens
  objects up to 32 MiB.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>