Access Violation (0xC0000005) error in memcpy() from libzmq call

[bbrancke]

My .Net app (4.7) crashes really hard under certain conditions. I attach to it using VS2017 debugger and the app runs for a while then: BOOM!

Exception thrown at 0x00000000743FBF7C (msvcr100.dll) in MyUI.exe: 0xC0000005:
Access violation reading location 0x000000001EE6FFFF. occurred

Disassembly window reveals:
memcpy(void) ["(void)" - sic]
116:
00000000743FBF75 je mcpy00+26h (0743FBFADh)
117:
.beginepilog
00000000743FBF77 test cl,1
118:
pop rsi
00000000743FBF7A je mcpy00 (0743FBF87h)
pop rdi
00000000743FBF7C mov al,byte ptr [rdx+rcx] <====== HERE !!!
ret ; return
00000000743FBF7F dec r8

00000000743FBF82 mov byte ptr [rcx],al
NESTED_END memcpy_repmovs, _TEXT
...

=============
Call Stack Window:
msvcr100.dll!memcpy() Line 119
at f:\dd\vctools\crt_bld\SELF_64_amd64\crt\src\amd64\memcpy.asm(119)
libzmq-x64-3.0.0.0.dll!000007fec17c66c6()
libzmq-x64-3.0.0.0.dll!000007fec17c0715()
libzmq-x64-3.0.0.0.dll!000007fec17b299d()
libzmq-x64-3.0.0.0.dll!000007fec17a8190()
libzmq-x64-3.0.0.0.dll!000007fec17b86e1()
libzmq-x64-3.0.0.0.dll!000007fec17c482d()
msvcr100.dll!_callthreadstartex() Line 314
at f:\dd\vctools\crt_bld\self_64_amd64\crt\src\threadex.c(314)
msvcr100.dll!_threadstartex(void * ptd) Line 292
at f:\dd\vctools\crt_bld\self_64_amd64\crt\src\threadex.c(292)
kernel32.dll!BaseThreadInitThunk()
ntdll.dll!RtlUserThreadStart()

Perhaps you've already seen and fixed this in later versions?

Is there a symbols (.PDB) file for zibzmq-x64-3.0.0.0 that might help to reveal a bad / closed ZMQ Context or Socket? I am (pretty sure) the ZMQ Contexts sockets are OK...

I can send a dump file if that would help.

Thanks a lot,
Brad Brancke
bbrancke@gmail.com