Fixed nullptr crash in ETH IP comparing code

[Tarik2142]

This PR fixes a nullptr crash when using ethernet.
The current implementation treats the passed value as a pointer, and since it is 0, it causes a crash.

Сomparing with IPAddress() is a more reliable option.

Summary by CodeRabbit

• Bug Fixes
  • Improved Ethernet static IP configuration validation.
  • Static IP and gateway settings are now applied only when valid network configuration data is available.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

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📥 Commits

Reviewing files that changed from the base of the PR and between d9b9a84 and c36fd97.

📒 Files selected for processing (1)

• wled00/network.cpp

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Walkthrough

The Ethernet static IP configuration check now requires a multiWiFi entry and non-default IPAddress values for the static IP and gateway before applying ETH.config.

Changes

Ethernet static IP configuration

Layer / File(s)	Summary
Validate Ethernet settings wled00/network.cpp	The static Ethernet configuration check now guards against an empty multiWiFi list and compares staticIP and staticGW with default IPAddress values.

Estimated code review effort: 1 (Trivial) | ~5 minutes

Suggested reviewers: softhack007

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly describes the main change: fixing a nullptr crash in Ethernet IP comparison code.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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[softhack007]

@Tarik2142 can you explain a bit more on which build this crash is happening?

• WLED version
• using a "V4" build (16.0.1) or a "V5" (17.0.0-devV5) ?

The cast to (uint32_t) was added to enforce that the uint32_t overload of "==" gets used, this overload should also handle nullptr properly - at least in the new framework.

[softhack007]

It might be that the addition of if (multiWiFi.size() is the actual fix.

@coderabbitai how is IPAddress() defined? Is it the same as 0.0.0.0 ?

[coderabbitai]

🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
set -euo pipefail

printf '%s\n' '=== IPAddress declarations/uses ==='
rg -n -C 3 'class IPAddress|IPAddress::IPAddress|IPAddress\(\)' \
  -g '*.{h,hpp,cpp,ino}' .

printf '%s\n' '=== Arduino-ESP32 framework version references ==='
rg -n -C 2 'arduino-esp32|ESP_ARDUINO_VERSION|platform.*espressif32' \
  -g 'platformio.ini' -g 'platformio*.ini' -g 'package.json' -g '*.json' -g '*.md' .

Length of output: 14902

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@softhack007, yes. In Arduino-ESP32, a default-constructed IPAddress() has all four IPv4 octets set to zero. It represents 0.0.0.0.

The two changes address different conditions:

• multiWiFi.size() prevents access to multiWiFi[0] when the vector is empty. This can be the crash fix if no Wi-Fi entry exists.
• staticIP != IPAddress() and staticGW != IPAddress() compare two IPAddress objects. This selects the IPAddress comparison overload.

The old (uint32_t)0x00000000 value can convert to a null pointer. It then selects the const uint8_t * comparison overload shown in the Comment image. That overload reads the pointer as address bytes, so it can dereference nullptr.

Therefore, IPAddress() is the correct explicit test for 0.0.0.0, and multiWiFi.size() is the required bounds guard. Both changes are valid.
🐇🔍

_{You are interacting with an AI system.}

[Tarik2142]

@Tarik2142 can you explain a bit more on which build this crash is happening?

• WLED version
• using a "V4" build (16.0.1) or a "V5" (17.0.0-devV5) ?

The cast to (uint32_t) was added to enforce that the uint32_t overload of "==" gets used, this overload should also handle nullptr properly - at least in the new framework.

I am working on a fork for ESP32-S3 + W5500 ethernet https://github.com/smlight-tech/A1-SLWF-09-WLED
And I found this crash on the S3 variant, I didn't check for the regular ESP32.
Crash dump looks like this:

I can say for sure that multiWiFi.size() is not the fix. I added that first but it didn't work. Then I replaced (uint32_t)0x00000000 and it fixed.