Fix multiple dumps from being generated

[mikem8361]

Issue: #78956

After a core dump is generated because of a unhandled managed exception abort() is called but a SIGSEGV is generated in libpthread.so which is caught by the runtime and a second core dump is generated. The fix is to uninstall/uninitialize all the signal handlers, not just SIGABORT.

[hoyosjs]

cc: @janvorli

[janvorli]

@mikem8361 do you have any details on why the SIGSEGV might be happening at all? Nevertheless, this change is good.

[hoyosjs]

We've only been able to repro in AKS, and we didn't have a set of symbols available.

[mikem8361]

Here is the stack trace from the second dump where abort() calls libpthread_2_31!funlockfile() which generates a SIGSEGV/generates this dump. Not sure that helps much.

00007f70`97a7b470 00007f70`988d58b3     libc_2_31!wait4+0x57
00007f70`97a7b4a0 00007f70`988d631f     libcoreclr!PROCCreateCrashDump+0x223 [/__w/1/s\src/coreclr/pal/src/thread/process.cpp @ 2465]
00007f70`97a7b500 00007f70`9889e0b0     libcoreclr!PROCCreateCrashDumpIfEnabled+0x2ff [/__w/1/s\src/coreclr/pal/src/thread/process.cpp @ 2654]
00007f70`97a7b580 00007f70`98f8d140     libcoreclr!sigsegv_handler+0x260 [/__w/1/s\src/coreclr/pal/src/exception/signal.cpp @ 15732480]
00007f70`97a7bac0 00007f70`98a96602     libpthread_2_31!funlockfile+0x50
00007fff`b5fcc330 00007f70`988d3b8b (T) libc_2_31!abort+0x1ee
00007fff`b5fcc460 00007f70`988d3ac0 (T) libcoreclr!PROCAbort+0x26 [/__w/1/s\src/coreclr/pal/src/thread/process.cpp @ 2684]
00007fff`b5fcc480 00007f70`986963e5     libcoreclr!PROCEndProcess+0xeb [/__w/1/s\src/coreclr/pal/src/thread/process.cpp @ 1342]
00007fff`b5fcc4b0 00007f70`986964c6     libcoreclr!UnwindManagedExceptionPass1+0x425 [/__w/1/s\src/coreclr/vm/exceptionhandling.cpp @ 4680]
00007fff`b5fccad0 00007f70`985e7cd9     libcoreclr!DispatchManagedException+0x86 [/__w/1/s\src/coreclr/vm/exceptionhandling.cpp @ 15732480]
00007fff`b5fccfd0 00007f70`19ff0b07     libcoreclr!IL_Throw+0x239 [/__w/1/s\src/coreclr/vm/jithelpers.cpp @ 15732480]
Unable to load image /app/CrashingApplication.dll, Win32 error 0n2
*** WARNING: Unable to verify checksum for CrashingApplication.dll
00007fff`b5fcd150 00007f70`9874b237     CrashingApplication!Program.<Main>$(System.String[])+0x77

[mikem8361]

/backport to release/7.0

[github-actions]

Started backporting to release/7.0: https://github.com/dotnet/runtime/actions/runs/3933111844