Segmentation fault in some control methods on x86_64

[Code-Hex]

This reintroduces code which was removed in 481c580.
The Block_copy/Block_release calls from this helper seem to be needed on my
x86_64 macOS11 machine. Without this, example/linux/virtualization segfaults
in startWithCompletionHandler.

This fixes this ASAN error:

=================================================================
==56003==ERROR: AddressSanitizer: requested allocation size 0x53cb4e83f8b48 (0x53cb4e83f9b48 after adjustments for alignment, red zones etc.) exceeds maximum supported size of 0x10000000000 (thread T6)
    #0 0x43f0400 in wrap_malloc+0xa0 (libclang_rt.asan_osx_dynamic.dylib:x86_64h+0x44400)
    #1 0x7fff205753ba in _Block_copy+0x5e (libsystem_blocks.dylib:x86_64+0x13ba)
    #2 0x7fff6f594307 in Base::BlockPtr<void (bool)> Base::BlockPtr<void (bool)>::from_callable<-[VZVirtualMachine startWithCompletionHandler:]::$_13>(-[VZVirtualMachine startWithCompletionHandler:]::$_13)::'lambda'(void*, bool)::__invoke(void*, bool)+0xb37 (Virtualization:x86_64+0x24307)
    #3 0x43ef5fa in __wrap_dispatch_async_block_invoke+0xca (libclang_rt.asan_osx_dynamic.dylib:x86_64h+0x435fa)
    #4 0x7fff20691622 in _dispatch_call_block_and_release+0xb (libdispatch.dylib:x86_64+0x2622)
    #5 0x7fff20692805 in _dispatch_client_callout+0x7 (libdispatch.dylib:x86_64+0x3805)
    #6 0x7fff206985e9 in _dispatch_lane_serial_drain+0x25d (libdispatch.dylib:x86_64+0x95e9)
    #7 0x7fff206990ac in _dispatch_lane_invoke+0x16d (libdispatch.dylib:x86_64+0xa0ac)
    #8 0x7fff206a2c0c in _dispatch_workloop_worker_thread+0x32a (libdispatch.dylib:x86_64+0x13c0c)
    #9 0x7fff2083945c in _pthread_wqthread+0x139 (libsystem_pthread.dylib:x86_64+0x345c)
    #10 0x7fff2083842e in start_wqthread+0xe (libsystem_pthread.dylib:x86_64+0x242e)

Post by @cfergeau #46

[cfergeau]

I've updated https://github.com/cfergeau/vz/commits/asan with tests which can be used to test the suggested fix in that same branch.

[cfergeau]

See #46 (comment) for CI changes reproducing this problem

[Code-Hex]

I tried on this branch master...issue-50
However, It's not reproduced now. (But I need o fix a few other points. I will fix it by adding tests #69) So I close this issue.

---

I have carefully observed the logs here (you reported). I made sure that the trace always contains getUUID. Perhaps #47 has been resolved at the root cause.

https://github.com/cfergeau/vz/actions/runs/3089765099/jobs/4997751402

[cfergeau]

I tried on this branch master...issue-50
However, It's not reproduced now.

I managed to reproduce with current master: https://github.com/cfergeau/vz/actions/runs/3244632281
Changes on top of your issue-50 branch are:

diff --git a/.github/workflows/compile.yml b/.github/workflows/compile.yml
index 5bf85ac..e9b6524 100644
--- a/.github/workflows/compile.yml
+++ b/.github/workflows/compile.yml
@@ -25,6 +25,7 @@ jobs:
       fail-fast: false
       matrix:
         os:
+        - macOS-11
         - macOS-12
         go:
         - 1.17
diff --git a/Makefile b/Makefile
index 94d8f6c..ac214d0 100644
--- a/Makefile
+++ b/Makefile
@@ -4,4 +4,4 @@ fmt:
 
 .PHONY: test
 test:
-       CGO_CFLAGS="-fsanitize=address" CGO_LDFLAGS="-fsanitize=address" CGO_ENABLED=1 go test -exec "go run $(PWD)/cmd/codesign" -count=1 ./...
+       CGO_ENABLED=1 go test -exec "go run $(PWD)/cmd/codesign" -count=1 ./...
diff --git a/check_test.go b/check_test.go
index 2bc6fd2..78385e4 100644
--- a/check_test.go
+++ b/check_test.go
@@ -36,6 +36,8 @@ func TestVM(t *testing.T) {
                t.Fatal("cannot start")
        }
        m.Start(func(err error) {
-               t.Error(err)
+               if err == nil {
+                       t.Fatal("Start() did not return an error")
+               }
        })
 }

I can no longer reproduce with asan enabled, which is odd. Maybe this is caused by some memory corruption.

[Code-Hex]

I tried to cherry-pick your this commit. but the commit does not exist now.

So I created again as a new PR for this fix. thanks for your report!

#74