fix: prevent unbounded tar layer allocation

[anwesha-palit-redhat]

Changes

Previously, readTarLayer used the tar header's declared size directly in make([]byte, header.Size), allowing a malicious bundle to specify an arbitrarily large size and potentially cause the CLI to exhaust available memory and crash.

Updated readTarLayer to use a bounded reader with a 1.5 MiB maximum layer size, preventing attacker-controlled tar metadata or oversized layer contents from causing excessive memory allocation. Added regression coverage to verify that layers exceeding the maximum size are rejected.

Signed-off-by: Anwesha Palit [apalit@redhat.com]

Assisted-by: Claude Opus 4.6

Submitter Checklist

These are the criteria that every PR should meet, please check them off as you
review them:

• Includes tests (if functionality changed/added)
• Run the code checkers with make check
• Regenerate the manpages, docs and go formatting with make generated
• Commit messages follow commit message best practices

See the contribution guide
for more details.

Release Notes

NONE

[Copilot]

🟢 Approval recommended

The bounded read and regression coverage address the vulnerability with no unresolved issues.

Pull request overview

Prevents excessive memory allocation when reading untrusted bundle tar layers.

Changes:

• Limits layer reads to 10 MiB.
• Rejects oversized layers with a clear error.
• Adds regression tests and updates test helpers.

File summaries

File	Description
pkg/cmd/bundle/push_test.go	Uses bounded layer reads in push tests.
pkg/bundle/reader.go	Enforces the layer size limit.
pkg/bundle/reader_test.go	Tests oversized-layer rejection.
pkg/bundle/builder_test.go	Uses bounded layer reads in builder tests.

Review details

• Files reviewed: 4/4 changed files
• Comments generated: 0
• Review effort level: Balanced

---

💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.

[divyansh42]

Thanks @anwesha-palit-redhat
Overall it looks good, I just have a minor comment regarding the test files.

maxLayerSize is hardcoded as 10 << 20 in three test files separately from
the constant in reader.go. If the limit in reader.go changes,
the test copies won't catch the drift — no compiler error will surface it.
Consider exporting the constant (e.g. MaxLayerSize) from reader.go so
tests can reference it directly instead of duplicating the value.

[tekton-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: divyansh42

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [divyansh42]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment

[anwesha-palit-redhat]

/retest

[divyansh42]

/retest

[anwesha-palit-redhat]

/retest

[divyansh42]

/retest

[Copilot]

🟡 Changes recommended

The layer-size limit is incorrectly set to 1.5 MiB instead of 10 MiB.

Once you've addressed the issues Copilot identified, you can request another Copilot review.

Review details

• Files reviewed: 4/4 changed files
• Comments generated: 1
• Review effort level: Balanced

[divyansh42]

/cc @vdemeester @pratap0007

[anwesha-palit-redhat]

/cherry-pick release-v0.44.x

[anwesha-palit-redhat]

/cherry-pick release-v0.45.x

[savitaashture]

LGTM

[pratap0007]

/lgtm

[pratap0007]

/cherry-pick release-v0.46.x

[tekton-robot]

✅ Cherry-pick to release-v0.46.x successful!

A new pull request has been created to cherry-pick this change to release-v0.46.x.

Please review and merge the cherry-pick PR.

[pratap0007]

/cherry-pick release-v0.45.x

[tekton-robot]

✅ Cherry-pick to release-v0.45.x successful!

A new pull request has been created to cherry-pick this change to release-v0.45.x.

Please review and merge the cherry-pick PR.

[pratap0007]

/cherry-pick release-v0.44.x

[pratap0007]

/cherry-pick release-v0.37.x

[tekton-robot]

✅ Cherry-pick to release-v0.44.x successful!

A new pull request has been created to cherry-pick this change to release-v0.44.x.

Please review and merge the cherry-pick PR.

[tekton-robot]

❌ Cherry-pick to release-v0.37.x failed!

The automatic cherry-pick to release-v0.37.x failed.

Output:

🤖 Starting cherry-pick process...
Fetching PR #3201 information...
Found merge commit: bb57149f2ea2d1e3f3c16c7fe0d849657103a47a
PR title: fix: prevent unbounded tar layer allocation
Fetching target branch: release-v0.37.x...
From https://github.com/tektoncd/cli
 * branch                release-v0.37.x -> FETCH_HEAD
Checking for existing cherry-pick PR...
Creating cherry-pick branch: cherry-pick-3201-to-release-v0.37.x...
Switched to a new branch 'cherry-pick-3201-to-release-v0.37.x'
branch 'cherry-pick-3201-to-release-v0.37.x' set up to track 'origin/release-v0.37.x'.
Cherry-picking commit bb57149f2ea2d1e3f3c16c7fe0d849657103a47a...
Auto-merging pkg/bundle/reader.go
CONFLICT (content): Merge conflict in pkg/bundle/reader.go
error: could not apply bb57149f2... fix: prevent unbounded tar layer allocation
hint: After resolving the conflicts, mark them with
hint: "git add/rm <pathspec>", then run
hint: "git cherry-pick --continue".
hint: You can instead skip this commit with "git cherry-pick --skip".
hint: To abort and get back to the state before "git cherry-pick",
hint: run "git cherry-pick --abort".
hint: Disable this message with "git config set advice.mergeConflict false"
❌ ERROR: Cherry-pick failed due to conflicts or other errors.

Next steps:

• Check the action logs for complete details
• If the PR is not merged, merge it first and try again
• If there are conflicts, you'll need to manually cherry-pick this PR