ldid-procursus Unbounded Memory Growth Bug: Zero-Valued Entitlement Integers in VPhone-CLI

The ldid-procursus unbounded memory growth bug is triggered when the code-signing utility processes an entitlement plist containing integer fields set to 0, causing repeated internal buffer reallocations without proper memory release during binary re-signing operations.

The Lakr233/vphone-cli repository relies on ldid-procursus for code-signing operations during iOS toolchain installations. When this utility encounters zero-valued entitlement integers in property list files, it enters an unbounded memory allocation loop that eventually exhausts system resources and terminates the host process.

Understanding the ldid-procursus Memory Bug Mechanism

The bug originates in how ldid-procursus parses entitlement plists during the signing process. When the tool processes an entitlement dictionary containing an integer field with a value of 0, it mishandles the parsing logic by repeatedly reallocating internal buffers instead of releasing previously allocated memory.

According to the source code in scripts/setup_tools.sh, which lists ldid-procursus as a required dependency, this defect becomes particularly destructive during iterative signing operations. The vulnerability activates specifically when the -S (apply-entitlements) and -M (use-certificate) flags are passed to ldid with an entitlement file containing zero-valued integers.

Source Files Triggering the Bug in VPhone-CLI

scripts/cfw_install.sh Host-Side Signing Loop

The primary trigger point resides in scripts/cfw_install.sh, which implements a wrapper function for applying entitlements to multiple binaries:

# scripts/cfw_install.sh – ldid signing wrapper

ldid_sign_ent() {
    # Apply a plist of entitlements to $file

    ldid "${args[@]}" "$file"
}

This function is invoked within a loop that processes every binary in the CFW payload:

# scripts/cfw_install.sh – iterate over all binaries in the CFW payload

for file in "$TEMP_DIR"/*; do
    ldid_sign "$file"
done

When ldid_sign_ent processes an entitlement plist containing zero-valued integers, each iteration contributes to cumulative memory growth until the process crashes.

scripts/vphoned/vphoned_install.m Guest-Side Operations

The guest-side installer at scripts/vphoned/vphoned_install.m extracts existing entitlements using ldid -e and re-signs binaries. If the extracted entitlement plist contains integer fields set to 0, the re-signing operation triggers the same memory exhaustion pattern.

scripts/cfw_install_dev.sh Development Variant

The file scripts/cfw_install_dev.sh uses the same signing wrapper logic as the main installer, making it equally vulnerable to the memory growth bug when processing binaries with problematic entitlement plists.

The Zero-Valued Integer Trigger Condition

The precise condition that activates this vulnerability is the presence of an integer value of 0 within the entitlement dictionary. For example:

<!-- example entitlements.plist -->
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>com.apple.private.security.no-container</key>
    <integer>0</integer>
    <key>com.apple.private.security.container-required</key>
    <string>com.example.app</string>
</dict>
</plist>

In this structure, the com.apple.private.security.no-container key with an integer value of 0 causes ldid-procursus to enter an infinite reallocation loop during plist parsing. The tool fails to properly handle the zero-value case, leaking memory with each parsing attempt until the operating system kills the process.

Impact on CFW Installation Workflows

During the CFW (Custom Firmware) installation process, the scripts repeatedly invoke ldid to sign multiple binaries sequentially. When any binary in the sequence includes zero-valued entitlement integers:

1. The ldid process begins parsing the entitlement plist
2. Encountering the zero-valued integer triggers the buffer reallocation bug
3. Memory usage grows unbounded with each successive binary processed
4. The system eventually terminates the process due to memory exhaustion

This behavior disrupts automated installations and requires manual intervention to identify and remove problematic entitlement values from the signing pipeline.

Summary

• Root Cause: ldid-procursus mishandles zero-valued integers in entitlement plists by repeatedly reallocating buffers without releasing memory.
• Trigger Condition: Any entitlement plist containing <integer>0</integer> values passed to ldid with -S and -M flags.
• Affected Files: scripts/cfw_install.sh, scripts/cfw_install_dev.sh, and scripts/vphoned/vphoned_install.m in the Lakr233/vphone-cli repository.
• Resolution: Remove zero-valued integers from entitlement files or upgrade to a patched version of ldid-procursus that properly handles integer parsing.

Frequently Asked Questions

What exactly causes the ldid-procursus memory leak?

The memory leak occurs when ldid-procursus parses an entitlement property list containing integer fields with values set to 0. The tool's plist parser repeatedly reallocates internal memory buffers instead of properly releasing them, causing unbounded memory growth during the signing operation.

Which VPhone-CLI scripts are most affected by this bug?

The installation scripts scripts/cfw_install.sh and scripts/cfw_install_dev.sh are most vulnerable because they iterate over multiple binaries and invoke ldid repeatedly. Additionally, scripts/vphoned/vphoned_install.m can trigger the bug during guest-side entitlement extraction and re-signing operations.

How can I prevent the unbounded memory growth when using ldid?

To prevent this issue, audit your entitlement plist files to ensure no integer fields contain the value 0. Replace zero-valued integers with appropriate boolean values (<true/> or <false/>) or remove the keys entirely if they are not required. Alternatively, upgrade to a patched version of ldid-procursus that properly handles zero-valued integers.

Does this bug affect all versions of ldid-procursus?

The bug specifically affects versions of ldid-procursus used by the VPhone-CLI toolchain as specified in scripts/setup_tools.sh. Versions that improperly parse integer values in property lists are vulnerable, while patched releases correct the buffer management logic to handle zero values appropriately.

{
  "mcpServers": {
    "instagit": {
      "command": "npx",
      "args": ["-y", "instagit@latest"]
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}