code review 6811080: archive/zip: Fix bounds check panic for ZIP files with ...

src/pkg/archive/zip/reader.go

Index: src/pkg/archive/zip/reader.go 
=================================================================== 
--- a/src/pkg/archive/zip/reader.go 
+++ b/src/pkg/archive/zip/reader.go 
@@ -238,7 +238,7 @@ 
 
	if len(f.Extra) > 0 { 
	b := readBuf(f.Extra) 
-	for len(b) > 0 { 
+	for len(b) > 4 { // need at least tag and size 
	tag := b.uint16() 
	size := b.uint16() 
	if int(size) > len(b) { 
@@ -259,6 +259,10 @@ 
	} 
	b = b[size:] 
	} 
+	// Should have consumed the whole header. 
+	if len(b) != 0 { 
+	return ErrFormat 
+	} 
	} 
	return nil 
 }