Skip to content

v5: *: Reject malformed variable-length integers#2092

Merged
pjbgf merged 1 commit into
go-git:releases/v5.xfrom
hiddeco:v5/validate-variable-length-integers
May 7, 2026
Merged

v5: *: Reject malformed variable-length integers#2092
pjbgf merged 1 commit into
go-git:releases/v5.xfrom
hiddeco:v5/validate-variable-length-integers

Conversation

@hiddeco

@hiddeco hiddeco commented May 7, 2026

Copy link
Copy Markdown
Member

Variable-length integer decoders accepted continuation chains long enough to push the running shift past the bit-width of their accumulator, producing out-of-range values that propagated into buffer allocation hints and on-disk size fields.

Mirror the bound from canonical Git's unpack_object_header_buffer1: reject any continuation byte that would shift past the type's capacity. The same rule applies to Scanner.readLength, the package-local decodeLEB128/decodeLEB128ByteReader, and ReadVariableWidthInt; decodeLEB128 now returns an error so callers surface invalid input rather than silently zeroing the result.

Add defense-in-depth at every call site that allocates from a parsed length: cap bytes.Buffer.Grow hints in the parser at 1 GiB, clamp the slice and maps initialized from Parser.count at a 4 Mi-entry hint so a hostile object count cannot request a multi-gigabyte allocation, and validate OFS-delta back-references in the scanner (must be > 0 and <= h.Offset).

Cover the new behavior with unit, parser-level regression and fuzz tests (FuzzReadLength, FuzzDecodeLEB128,
FuzzDecodeLEB128ByteReader, FuzzParser).

Backport of #2090.

Comment thread utils/binary/read.go Outdated
Comment thread plumbing/format/packfile/patch_delta.go Outdated
Variable-length integer decoders accepted continuation chains long
enough to push the running shift past the bit-width of their
accumulator, producing out-of-range values that propagated into
buffer allocation hints and on-disk size fields.

Mirror the bound from canonical Git's `unpack_object_header_buffer`[1]:
reject any continuation byte that would shift past the type's
capacity. The same rule applies to `Scanner.readLength`, the
package-local `decodeLEB128`/`decodeLEB128ByteReader`, and
`ReadVariableWidthInt`; `decodeLEB128` now returns an error so
callers surface invalid input rather than silently zeroing the
result.

Add defense-in-depth at every call site that allocates from a
parsed length: cap `bytes.Buffer.Grow` hints in the parser at
1 GiB, clamp the slice and maps initialized from `Parser.count`
at a 4 Mi-entry hint so a hostile object count cannot request a
multi-gigabyte allocation, and validate `OFS-delta` back-references
in the scanner (must be `> 0` and `<= h.Offset`).

Cover the new behavior with unit, parser-level regression and
fuzz tests (`FuzzReadLength`, `FuzzDecodeLEB128`,
`FuzzDecodeLEB128ByteReader`, `FuzzParser`).

[1]: https://github.com/git/git/blob/v2.54.0/packfile.c#L1135-L1158

Backport of go-git#2090.

Assisted-by: Claude Opus 4.7
Signed-off-by: Hidde Beydals <hidde@hhh.computer>
@hiddeco hiddeco force-pushed the v5/validate-variable-length-integers branch from f544e00 to 3512272 Compare May 7, 2026 21:35

@pjbgf pjbgf left a comment

Copy link
Copy Markdown
Member

Choose a reason for hiding this comment

The reason will be displayed to describe this comment to others. Learn more.

@hiddeco thanks for working on this. 🙇

@pjbgf pjbgf merged commit 3ef4f3e into go-git:releases/v5.x May 7, 2026
9 checks passed
@hiddeco hiddeco deleted the v5/validate-variable-length-integers branch May 7, 2026 22:17
chhe pushed a commit to chhe/act_runner that referenced this pull request May 19, 2026
This PR contains the following updates:

| Package | Change | [Age](https://docs.renovatebot.com/merge-confidence/) | [Confidence](https://docs.renovatebot.com/merge-confidence/) |
|---|---|---|---|
| [github.com/go-git/go-git/v5](https://github.com/go-git/go-git) | `v5.19.0` → `v5.19.1` | ![age](https://developer.mend.io/api/mc/badges/age/go/github.com%2fgo-git%2fgo-git%2fv5/v5.19.1?slim=true) | ![confidence](https://developer.mend.io/api/mc/badges/confidence/go/github.com%2fgo-git%2fgo-git%2fv5/v5.19.0/v5.19.1?slim=true) |

---

### Release Notes

<details>
<summary>go-git/go-git (github.com/go-git/go-git/v5)</summary>

### [`v5.19.1`](https://github.com/go-git/go-git/releases/tag/v5.19.1)

[Compare Source](go-git/go-git@v5.19.0...v5.19.1)

#### What's Changed

- v5: plumbing: transport/ssh, Shell-quote path by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2068](go-git/go-git#2068)
- v5: git: submodule, Fix relative URL resolution by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2070](go-git/go-git#2070)
- v5: git: submodule, canonical remote for relative URLs by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2074](go-git/go-git#2074)
- v5: git: submodule, error on remote without URLs by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2078](go-git/go-git#2078)
- v5: plumbing: format/idxfile, Validate offset64 indices by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2084](go-git/go-git#2084)
- v5: \*: Reject malformed variable-length integers by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2092](go-git/go-git#2092)
- v5: plumbing: format/packfile, Tighten delta validation by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2091](go-git/go-git#2091)
- v5: Add `worktreeFilesystem` wrapper for worktree and hardening by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2100](go-git/go-git#2100)
- v5: config: validate submodule names by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2082](go-git/go-git#2082)
- build: Update module github.com/go-git/go-git/v5 to v5.19.0 \[SECURITY] (releases/v5.x) by [@&#8203;go-git-renovate](https://github.com/go-git-renovate)\[bot] in [#&#8203;2111](go-git/go-git#2111)
- v5: git: Allow MkdirAll on worktree-root paths by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2117](go-git/go-git#2117)
- v5: git: Stop validating symlink target paths by [@&#8203;pjbgf](https://github.com/pjbgf) in [#&#8203;2116](go-git/go-git#2116)
- v5: plumbing: format decoder input bounds and contracts by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2125](go-git/go-git#2125)
- plumbing: format/packfile, cap delta chain depth in parser by [@&#8203;pjbgf](https://github.com/pjbgf) in [#&#8203;2137](go-git/go-git#2137)

**Full Changelog**: <go-git/go-git@v5.19.0...v5.19.1>

</details>

---

### Configuration

📅 **Schedule**: (UTC)

- Branch creation
  - At any time (no schedule defined)
- Automerge
  - At any time (no schedule defined)

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

---

This PR has been generated by [Mend Renovate](https://github.com/renovatebot/renovate).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0My4xODIuMSIsInVwZGF0ZWRJblZlciI6IjQzLjE4Mi4xIiwidGFyZ2V0QnJhbmNoIjoibWFpbiIsImxhYmVscyI6W119-->

Reviewed-on: https://gitea.com/gitea/runner/pulls/980
Reviewed-by: Lunny Xiao <xiaolunwen@gmail.com>
Co-authored-by: Renovate Bot <renovate-bot@gitea.com>
Co-committed-by: Renovate Bot <renovate-bot@gitea.com>
Maks1mS pushed a commit to stplr-dev/stplr that referenced this pull request May 20, 2026
This PR contains the following updates:

| Package | Type | Update | Change | OpenSSF |
|---|---|---|---|---|
| [github.com/go-git/go-git/v5](https://github.com/go-git/go-git) | require | patch | `v5.19.0` → `v5.19.1` | [![OpenSSF Scorecard](https://api.securityscorecards.dev/projects/github.com/go-git/go-git/badge)](https://securityscorecards.dev/viewer/?uri=github.com/go-git/go-git) |

---

> ⚠️ **Warning**
>
> Some dependencies could not be looked up. Check the [Dependency Dashboard](issues/23) for more information.

---

### Release Notes

<details>
<summary>go-git/go-git (github.com/go-git/go-git/v5)</summary>

### [`v5.19.1`](https://github.com/go-git/go-git/releases/tag/v5.19.1)

[Compare Source](go-git/go-git@v5.19.0...v5.19.1)

#### What's Changed

- v5: plumbing: transport/ssh, Shell-quote path by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2068](go-git/go-git#2068)
- v5: git: submodule, Fix relative URL resolution by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2070](go-git/go-git#2070)
- v5: git: submodule, canonical remote for relative URLs by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2074](go-git/go-git#2074)
- v5: git: submodule, error on remote without URLs by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2078](go-git/go-git#2078)
- v5: plumbing: format/idxfile, Validate offset64 indices by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2084](go-git/go-git#2084)
- v5: \*: Reject malformed variable-length integers by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2092](go-git/go-git#2092)
- v5: plumbing: format/packfile, Tighten delta validation by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2091](go-git/go-git#2091)
- v5: Add `worktreeFilesystem` wrapper for worktree and hardening by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2100](go-git/go-git#2100)
- v5: config: validate submodule names by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2082](go-git/go-git#2082)
- build: Update module github.com/go-git/go-git/v5 to v5.19.0 \[SECURITY] (releases/v5.x) by [@&#8203;go-git-renovate](https://github.com/go-git-renovate)\[bot] in [#&#8203;2111](go-git/go-git#2111)
- v5: git: Allow MkdirAll on worktree-root paths by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2117](go-git/go-git#2117)
- v5: git: Stop validating symlink target paths by [@&#8203;pjbgf](https://github.com/pjbgf) in [#&#8203;2116](go-git/go-git#2116)
- v5: plumbing: format decoder input bounds and contracts by [@&#8203;hiddeco](https://github.com/hiddeco) in [#&#8203;2125](go-git/go-git#2125)
- plumbing: format/packfile, cap delta chain depth in parser by [@&#8203;pjbgf](https://github.com/pjbgf) in [#&#8203;2137](go-git/go-git#2137)

**Full Changelog**: <go-git/go-git@v5.19.0...v5.19.1>

</details>

---

### Configuration

📅 **Schedule**: (UTC)

- Branch creation
  - At 12:00 AM through 04:59 AM and 10:00 PM through 11:59 PM, Monday through Friday (`* 0-4,22-23 * * 1-5`)
  - Only on Sunday and Saturday (`* * * * 0,6`)
- Automerge
  - At any time (no schedule defined)

🚦 **Automerge**: Disabled by config. Please merge this manually once you are satisfied.

♻ **Rebasing**: Whenever PR becomes conflicted, or you tick the rebase/retry checkbox.

🔕 **Ignore**: Close this PR and you won't be reminded about this update again.

---

 - [ ] <!-- rebase-check -->If you want to rebase/retry this PR, check this box

---

This PR has been generated by [Mend Renovate](https://github.com/renovatebot/renovate).
<!--renovate-debug:eyJjcmVhdGVkSW5WZXIiOiI0My4xNzAuMjIiLCJ1cGRhdGVkSW5WZXIiOiI0My4xNzAuMjIiLCJ0YXJnZXRCcmFuY2giOiJtYWluIiwibGFiZWxzIjpbIktpbmQvRGVwZW5kZW5jaWVzIl19-->

Reviewed-on: https://altlinux.space/stapler/stplr/pulls/435
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment

Labels

None yet

Projects

None yet

Development

Successfully merging this pull request may close these issues.

2 participants