The module in AverMedia Engine avmvirtualsource.ax seems to cause heap corruption in Firefox.

The associated signature RtlpFreeHeapInternal | RtlFreeHeap | APP_DATA::FreeCachedMem includes crashes caused by other reasons. The characteristics of this issue is avmvirtualsource.ax in the crash dump.

Crash report: https://crash-stats.mozilla.org/report/index/70545398-0ea3-4ace-833d-0975c0210213

Reason: EXCEPTION_HEAP_CORRUPTION

Top 10 frames of crashing thread:

0 ntdll.dll RtlReportFatalFailure 
1 ntdll.dll RtlReportCriticalFailure 
2 ntdll.dll RtlpHeapHandleError 
3 ntdll.dll RtlpHpHeapHandleError 
4 ntdll.dll RtlpLogHeapFailure 
5 ntdll.dll RtlpFreeHeapInternal 
6 ntdll.dll RtlFreeHeap 
7 oleaut32.dll void APP_DATA::FreeCachedMem 
8 oleaut32.dll SysFreeString 
9 avmvirtualsource.ax avmvirtualsource.ax@0x3279 

Probably https://www.reddit.com/r/firefox/comments/lj4ptv/firefox_immediately_crash_when_accessing_the/ is the same problem.

I did some repro effort.

<Installation>

1. Go to https://www.avermedia.com/us/support/download
2. Choose "Webcam" and "Live Streamer CAM 313 - PW313"
3. Download and install "AVerMedia CamEngine (Win) v2.0.0.51"

This package includes avmvirtualsource.ax 1.0.0.3, which I believe is the same file as in the crash.

<After installation>

1. Run regsvr32 avmvirtualsource.ax (somehow the installer does not register this file)
2. Go to https://webcammictest.com/
3. Choose "AVerMedia Cam Engine Source"

Now, avmvirtualsource.ax is loaded into firefox.exe, but neither webcam test or crash happens. Even worse, I hit a different crash https://bugzilla.mozilla.org/show_bug.cgi?id=1576335#c16 when I close Firefox. Maybe it's because I don't have an AVerMedia's device.

https://hg.mozilla.org/mozilla-central/rev/87304681d16b