fix: nocopy read add cap restraint

nocopy_linkbuffer.go

@@ -257,11 +257,11 @@ func (b *UnsafeLinkBuffer) readBinary(n int) (p []byte) {
 			// for example, if user's codec need to decode 10 strings and each have 100 bytes, here could help the codec
 			// no need to malloc 10 times and the string slice could have the compact memory allocation.
 			if b.read.getMode(nocopyReadMask) {
-				return b.read.Next(n)
+				return b.read.Next(n)[:n:n]
 			}
 			if n >= minReuseBytes && cap(b.read.buf) <= block32k {
 				b.read.setMode(nocopyReadMask, true)
-				return b.read.Next(n)
+				return b.read.Next(n)[:n:n]
 			}
 		}
 		// if the underlying buffer too large, we shouldn't use no-copy mode