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Hytale-F2P-2/docs/STEAMDECK_CRASH_INVESTIGATION.md
sanasol 9ec97f9d33 fix: Steam Deck/Ubuntu crash - use system libzstd.so
The bundled libzstd.so is incompatible with glibc 2.41's stricter heap
validation, causing "free(): invalid pointer" crashes.

Solution: Automatically replace bundled libzstd.so with system version
on Linux. The launcher detects and symlinks to /usr/lib/libzstd.so.1.

- Auto-detect system libzstd at common paths (Arch, Debian, Fedora)
- Backup bundled version as libzstd.so.bundled
- Create symlink to system version
- Add HYTALE_NO_LIBZSTD_FIX=1 to disable if needed

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
2026-01-27 19:40:42 +01:00

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# Steam Deck / Ubuntu LTS Crash Investigation
## Status: SOLVED
**Last updated:** 2026-01-27
**Solution:** Replace bundled `libzstd.so` with system version.
---
## Problem Summary
The Hytale F2P launcher's client patcher causes crashes on Steam Deck and Ubuntu LTS with the error:
```
free(): invalid pointer
```
or
```
SIGSEGV (Segmentation fault)
```
The crash occurs after successful authentication, specifically right after "Finished handling RequiredAssets".
**Affected Systems:**
- Steam Deck (glibc 2.41)
- Ubuntu LTS
**Working Systems:**
- macOS
- Windows
- Older Arch Linux (glibc < 2.41)
---
## Root Cause
The **bundled `libzstd.so`** in the game client is incompatible with glibc 2.41's stricter heap validation. When the game decompresses assets using this library, it triggers heap corruption detected by glibc 2.41.
The crash occurs in `libzstd.so` during `free()` after "Finished handling RequiredAssets" (asset decompression).
---
## Solution
Replace the bundled `libzstd.so` with the system's `libzstd.so.1`.
### Automatic (Launcher)
The launcher automatically detects and replaces `libzstd.so` on Linux systems. No manual action needed.
### Manual
```bash
cd ~/.hytalef2p/release/package/game/latest/Client
# Backup bundled version
mv libzstd.so libzstd.so.bundled
# Link to system version
# Steam Deck / Arch Linux:
ln -s /usr/lib/libzstd.so.1 libzstd.so
# Debian / Ubuntu:
ln -s /usr/lib/x86_64-linux-gnu/libzstd.so.1 libzstd.so
# Fedora / RHEL:
ln -s /usr/lib64/libzstd.so.1 libzstd.so
```
### Restore Original
```bash
cd ~/.hytalef2p/release/package/game/latest/Client
rm libzstd.so
mv libzstd.so.bundled libzstd.so
```
---
## Why This Works
1. The bundled `libzstd.so` was likely compiled with different allocator settings or an older toolchain
2. glibc 2.41 has stricter heap validation that catches invalid memory operations
3. The system `libzstd.so.1` is compiled with the system's glibc and uses compatible memory allocation patterns
4. By using the system library, we avoid the incompatibility entirely
---
## Previous Investigation (for reference)
### What Was Tried Before Finding Solution
| Approach | Result |
|----------|--------|
| jemalloc allocator | Worked ~30% of time, not stable |
| GLIBC_TUNABLES | No effect |
| taskset (CPU pinning) | Single core too slow |
| nice/chrt (scheduling) | No effect |
| Various patching approaches | All crashed |
### Key Insight
The crash was in `libzstd.so`, not in our patched code. The patching just changed timing enough to expose the libzstd incompatibility more frequently.
---
## GDB Stack Trace (Historical)
```
#0 0x00007ffff7d3f5a4 in ?? () from /usr/lib/libc.so.6
#1 raise () from /usr/lib/libc.so.6
#2 abort () from /usr/lib/libc.so.6
#3-#4 ?? () from /usr/lib/libc.so.6
#5 free () from /usr/lib/libc.so.6
#6 ?? () from libzstd.so <-- CRASH POINT (bundled library)
#7-#24 HytaleClient code (asset decompression)
```
---
## Branch
`fix/steamdeck-libzstd`