Crash report: https://crash-stats.mozilla.org/report/index/53d9102f-f127-4dd9-9091-22bbf0201120

MOZ_CRASH Reason: MOZ_RELEASE_ASSERT((run->mRegionsMask[elm] & (1U << bit)) == 0) (Double-free?)

Top 10 frames of crashing thread:

0 mozglue.dll static Allocator<MozJemallocBase>::free memory/build/malloc_decls.h:54
1 xul.dll FinalizeArenas js/src/gc/GC.cpp:566
2 xul.dll js::gc::BackgroundSweepTask::run js/src/gc/GC.cpp:3473
3 xul.dll js::GCParallelTask::runTask js/src/gc/GCParallelTask.cpp:145
4 xul.dll js::GCParallelTask::runHelperThreadTask js/src/gc/GCParallelTask.cpp:132
5 xul.dll static js::HelperThread::ThreadMain js/src/vm/HelperThreads.cpp:2355
6 xul.dll static js::detail::ThreadTrampoline<void  js/src/threading/Thread.h:206
7 ucrtbase.dll thread_start<unsigned int > 
8 kernel32.dll BaseThreadInitThunk 
9 ucrtbase.dll o_strcat_s 

Steps to reproduce:

1. Launch Firefox
2. Go to https://www.reddit.com/r/pics/
3. Scroll up and down using mouse wheel, scroll bar, arrow keys, page up/down keys, space bar, ctrl + up/down keys randomly

Additional notes:

• I've encountered this crash only once
• Not sure the component is the right one, feel free to change it to a suitable one.

Without STR this is not really actionable.

It's possible that this is due to bad memory or another hardware problem.

Closing because no crashes reported for 12 weeks.