fix dangerous uintptr conversion

[dangodangodango]

According to: https://pkg.go.dev/unsafe#Pointer Unsafe.Pointer rule 4:

For the compiler to recognize this pattern, the conversion must appear in the argument list:

// INVALID: uintptr cannot be stored in variable
// before implicit conversion back to Pointer during system call.
u := uintptr(unsafe.Pointer(p))
syscall.Syscall(SYS_READ, uintptr(fd), u, uintptr(n))

Storing a go pointer to uintptr variable is dangerous, the address of the go variable that the uintptr pointers to may change (stack grow), or the variable be garbage-collected(uintptr doesn't ref the value).
Even worse, the original address may be reused by another goroutine, and if the syscall writes to that address, it's can cause memory corruption and random runtime errors.

[dangodangodango]

@microsoft-github-policy-service agree