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Three-agent security audit of the LOCKDOWN build identified race conditions, incomplete key zeroing, and missing memory hygiene. All findings except HIGH-1 are addressed here. HIGH-1 (revokeAllAuth not resetting per-instance isAdminAuthorized) was reviewed and closed as wontfix: PKC admin key holders have persistent access regardless, so the 7-second pre-reboot window changes nothing about the threat model. HIGH-2: lockNow() previously only zeroed dek[]. Now also zeroes kek[], ephemeralKek[], and their derived flags so no key material survives a lock event in a RAM dump. HIGH-3: isAdminAuthorized (per-instance) and s_localAdminAuthorized (static) changed from plain bool to std::atomic<bool>. Both flags are written from the NimBLE FreeRTOS task and read from the main loop — non-atomic reads were a data race. MED-1: readAndDecrypt() and encryptAndWrite() now snapshot dek[] into a stack- local dekSnapshot[] on entry before acquiring any lock. A concurrent lockNow() that zeros dek[] mid-operation either zeroes the snapshot (HMAC fails securely) or has no effect on an already-captured copy. dekSnapshot is zeroed on all exit paths. MED-2: close() and handleStartConfig() no longer clear s_localAdminAuthorized. Resetting it on every disconnect was an auth DoS — any new client connection would silently revoke the passphrase-authenticated state, forcing the operator to re-enter the passphrase on every reconnect. Device-level auth now persists until explicit Lock Now (revokeAllAuth()). MED-3: readAndDecrypt() scoped the spiLock LockGuard to a nested block covering only the FSCom.open/read/close sequence. The lock is released before any HMAC or AES-CTR work. spiLock is a non-recursive binary semaphore; holding it across CC310 calls created a re-entry deadlock risk. MED-4: AdminModule zeros the passphrase bytes in toRadioScratch via a volatile pointer cast before returning from both the Lock Now and provision/unlock paths. Prevents the passphrase lingering in the scratch buffer until the next ToRadio message overwrites it. MED-5: readAndDecrypt() was missing memset(fileBuf) on the hmacData OOM early- exit path, leaving ciphertext in the heap until the allocator reuses it. MED-6: readAndDecrypt() now sets outLen=0 on entry so callers never observe a stale length value on any early failure return. MED-7: readAndDecrypt() calls memset(outBuf, 0, ciphertextLen) on AES-CTR failure to clear partial plaintext that may have been written to the caller's buffer before the error was detected. MED-8: Passphrase length limit corrected from 64 to 32 bytes throughout (EncryptedStorage.cpp provisionPassphrase/unlockWithPassphrase, AdminModule.cpp ppLen range check, EncryptedStorage.h doc comments). The proto private_key field is 32 bytes; accepting 33-64 silently failed inside EncryptedStorage while appearing to succeed at the AdminModule gate. L-1: readAndDecrypt() now rejects files larger than 65536+54 bytes before allocating the heap buffer, preventing OOM or integer overflow on corrupt or attacker-supplied oversized files. L-2: migrateFile() has a precondition comment that spiLock must not be held by the caller; both isEncrypted() and encryptAndWrite() acquire it internally.
Meshtastic Firmware
Overview
This repository contains the official device firmware for Meshtastic, an open-source LoRa mesh networking project designed for long-range, low-power communication without relying on internet or cellular infrastructure. The firmware supports various hardware platforms, including ESP32, nRF52, RP2040/RP2350, and Linux-based devices.
Meshtastic enables text messaging, location sharing, and telemetry over a decentralized mesh network, making it ideal for outdoor adventures, emergency preparedness, and remote operations.
Get Started
- 🔧 Building Instructions – Learn how to compile the firmware from source.
- ⚡ Flashing Instructions – Install or update the firmware on your device.
Join our community and help improve Meshtastic! 🚀
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