Merge pull request #7 from bersoare/bounds_check

check buffer length before accessing it

arping_bsd.go

@@ -96,6 +96,11 @@ func (s *BsdSocket) receive() (arpDatagram, time.Time, error) {
 	// skip bpf header + 14 bytes ethernet header
 	var hdrLength = bpfHdrLength + 14
 
+	if n <= hdrLength || len(buffer) <= hdrLength {
+		// amount of bytes read by socket is less than an ethernet header. clearly not what we look for
+		return arpDatagram{}, time.Now(), fmt.Errorf("buffer with invalid length")
+
+	}
 	return parseArpDatagram(buffer[hdrLength:n]), time.Now(), nil
 }
 

arping_linux.go

@@ -1,6 +1,7 @@
 package arping
 
 import (
+	"fmt"
 	"net"
 	"syscall"
 	"time"
@@ -34,6 +35,11 @@ func (s *LinuxSocket) receive() (arpDatagram, time.Time, error) {
 	if err != nil {
 		return arpDatagram{}, time.Now(), err
 	}
+	if n <= 14 {
+		// amount of bytes read by socket is less than an ethernet header. clearly not what we look for
+		return arpDatagram{}, time.Now(), fmt.Errorf("buffer with invalid length")
+
+	}
 	// skip 14 bytes ethernet header
 	return parseArpDatagram(buffer[14:n]), time.Now(), nil
 }