secondlife / secondlife/viewer
LLGroupMgr::removeObserver can fail to find and erase observers causing a crash
A pull request for this has already been merged.
- #6051 by @Hecklezz — merged
- Dominant language
- C++
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Description
Environment
Second Life Release 26.2.0.25386466510 (64bit)
Rest of Environment-
Release NotesCPU: Intel(R) Core(TM) i7-9700K CPU @ 3.60GHz (3600.01 MHz)
Memory: 16302 MB
OS Version: Microsoft Windows 10 64-bit (Build 19045.7548)
Graphics Card Vendor: NVIDIA Corporation
Graphics Card: NVIDIA GeForce RTX 2080/PCIe/SSE2
Windows Graphics Driver Version: 32.0.15.9636
OpenGL Version: 4.6.0 NVIDIA 596.36
Window size: 1920x1081
Font Size Adjustment: 96pt
UI Scaling: 1
Draw distance: 512m
Bandwidth: 10000kbit/s
LOD factor: 4
Render quality: 5
Texture memory: 8192MB
Disk cache: Max size 11468.8 MB (0.7% used)
J2C Decoder Version: KDU v8.4.1
Audio Driver Version: OpenAL, version 1.1 ALSOFT 1.24.2 / OpenAL Community / OpenAL Soft: OpenAL Soft
Dullahan: 1.24.0.202510081738
CEF: 139.0.40+g465474a+chromium-139.0.7258.139
Chromium: 139.0.7258.139
LibVLC Version: 3.0.21
Voice Server Version:
July 26 2026 10:31:33
Description
PR with possible fix: https://github.com/secondlife/viewer/pull/6051
Currently in the LLGroupMgr::removeObserver function here, the code is using std::multimap::find in order to get the first instance in the mObservers multimap and then iterate from there.
However this is incorrect and there is no guarantee that std::multimap::find will return the actual first instance in a multimap.
I observed recently crashes in LLGroupMgr::notifyObservers relating to LLGroupIconCtrl's where one of their observers had been deleted but it had never gotten erased from the mObservers in LLGroupMgr. This was because after some investigation, the mObservers.find was not returning the actual first instance of the corresponding observer id, so when it looped over the observers, it was never found and erased.
Reproduction steps
Cannot reproduce on demand, as this constitutes similar to undefined behaviour.
Contributor guide
First steps
- Read the whole issue, then the project's contributing guide.
- Comment on the issue to say you are picking it up — it saves two people doing the same work.
- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start in indra/newview/llgroupmgr.cpp at LLGroupMgr::removeObserver and review how mObservers is searched and traversed. Check linked pull request 6051, which is merged, before doing any work; the intended result is that observers are reliably found and erased so notifyObservers cannot retain deleted observers.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- cpp
- Domain
- game-dev
- Issue type
- Bug
- Difficulty
- 2/5
- Estimated time
- 1-3 hours
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 25/100