libgo: Update to Go 1.0.1 release.

[pf3gnuchains/gcc-fork.git] / libgo / go / encoding / asn1 / asn1.go

diff --git a/libgo/go/encoding/asn1/asn1.go b/libgo/go/encoding/asn1/asn1.go
index 3bf81a6..ac2b5f8 100644 (file)
--- a/libgo/go/encoding/asn1/asn1.go
+++ b/libgo/go/encoding/asn1/asn1.go
@@ -377,11 +377,6 @@ func parseTagAndLength(bytes []byte, initOffset int) (ret tagAndLength, offset i
        } else {
                // Bottom 7 bits give the number of length bytes to follow.
                numBytes := int(b & 0x7f)
-               // We risk overflowing a signed 32-bit number if we accept more than 3 bytes.
-               if numBytes > 3 {
-                       err = StructuralError{"length too large"}
-                       return
-               }
                if numBytes == 0 {
                        err = SyntaxError{"indefinite length found (not DER)"}
                        return
@@ -394,8 +389,19 @@ func parseTagAndLength(bytes []byte, initOffset int) (ret tagAndLength, offset i
                        }
                        b = bytes[offset]
                        offset++
+                       if ret.length >= 1<<23 {
+                               // We can't shift ret.length up without
+                               // overflowing.
+                               err = StructuralError{"length too large"}
+                               return
+                       }
                        ret.length <<= 8
                        ret.length |= int(b)
+                       if ret.length == 0 {
+                               // DER requires that lengths be minimal.
+                               err = StructuralError{"superfluous leading zeros in length"}
+                               return
+                       }
                }
        }