LockedBuffer.Copy() crashes with access violation on Windows when buffer is valid and alive #165
Description
Describe the bug
Calling (*memguard.LockedBuffer).Copy() results in a fatal access violation on Windows, even though the buffer is non-nil, alive (IsAlive() returns true), and accessed under a sync.RWMutex that guards against concurrent Destroy() or Swap().
Replacing .Copy() with copy(out, buf.Bytes()) avoids the issue.
To Reproduce
Steps to reproduce the behavior:
Create a LockedBuffer using memguard.NewBufferFromBytes
Call .Copy() into equally sized destination buffer
-> panic or access violation
buf := memguard.NewBufferFromBytes([]byte("test"))
defer buf.Destroy()
out := make([]byte, buf.Size())
buf.Copy(out)Expected behaviour
Copy() should copy memory from a valid, non-destroyed buffer.
It should not crash when:
- The buffer is alive
- The buffer size is non-zero
System:
OS and Kernel Versions: Microsoft Windows [Version 10.0.26100.3775]
Memguard Version: v0.22.5
Go Version: go1.24.1 (Windows amd64)
Additional context
- Tried with Mutex
- No concurrent calls to .Destroy() or .Swap()
- .IsAlive() returns true before .Copy()
- .Bytes() works fine under same locking conditions
- Switching to append([]byte(nil), buf.Bytes()...) avoids crash completely.