// what you wrote

var valueLength uint64
valuePtr := keyHandle.StringDMA(&valueLength, rm.READ)
var s string
hdr := (*reflect.StringHeader)(unsafe.Pointer(&s))
hdr.Data = uintptr(valuePtr)
hdr.Len = value
// use s, which points to redis string w/ correct length


// what I thought you wrote
valuePtr := keyHandle.StringDMA(&valueLength, rm.READ)
hdr := (*reflect.StringHeader)(valuePtr)
hdr.Data = uintptr(valuePtr)
hdr.Len = value
s := *(*string)(hdr)