Resolve map initialization order bug

debug/elf/file.go

@@ -244,6 +244,7 @@ func (f *File) SectionByType(typ SectionType) *Section {
 // NewFile creates a new File for accessing an ELF binary in an underlying reader.
 // The ELF binary is expected to start at position 0 in the ReaderAt.
 func NewFile(r io.ReaderAt) (*File, error) {
+
 	sr := io.NewSectionReader(r, 0, 1<<63-1)
 	// Read and decode ELF identifier
 	var ident [16]uint8
@@ -255,6 +256,7 @@ func NewFile(r io.ReaderAt) (*File, error) {
 	}
 
 	f := new(File)
+	f.dataAfterSectionCache = make(map[uint64][]byte)
 	f.Class = Class(ident[EI_CLASS])
 	switch f.Class {
 	case ELFCLASS32:
@@ -565,8 +567,6 @@ func NewFile(r io.ReaderAt) (*File, error) {
 			return nil, &FormatError{shoff + int64(i*shentsize), "bad section name index", names[i]}
 		}
 	}
-
-	f.dataAfterSectionCache = make(map[uint64][]byte)
 	return f, nil
 }
 

debug/macho/file.go

@@ -231,6 +231,7 @@ func (f *File) Close() error {
 // The Mach-O binary is expected to start at position 0 in the ReaderAt.
 func NewFile(r io.ReaderAt) (*File, error) {
 	f := new(File)
+	f.dataAfterSectionCache = make(map[uint64][]byte)
 	sr := io.NewSectionReader(r, 0, 1<<63-1)
 
 	// Read and decode Mach magic to determine byte order, size.
@@ -449,7 +450,6 @@ func NewFile(r io.ReaderAt) (*File, error) {
 			s.ReaderAt = s.sr
 		}
 	}
-	f.dataAfterSectionCache = make(map[uint64][]byte)
 	return f, nil
 }
 

debug/pe/file.go

@@ -67,6 +67,7 @@ func (f *File) Close() error {
 // NewFile creates a new File for accessing a PE binary in an underlying reader.
 func NewFile(r io.ReaderAt) (*File, error) {
 	f := new(File)
+	f.dataAfterSectionCache = make(map[uint64][]byte)
 	sr := io.NewSectionReader(r, 0, 1<<63-1)
 
 	var dosheader [96]byte
@@ -172,8 +173,6 @@ func NewFile(r io.ReaderAt) (*File, error) {
 			return nil, err
 		}
 	}
-
-	f.dataAfterSectionCache = make(map[uint64][]byte)
 	return f, nil
 }
 

main_test.go

@@ -188,6 +188,20 @@ func TestWeirdBins(t *testing.T) {
 			t.Errorf("GoReSym found pclntab in a non-go binary, this is not possible.")
 		}
 	})
+
+	// reading the buildid with notes section at the start and alignment of 0 previously caused underflow in offset calculations
+	t.Run("zero_elf_palignment", func(t *testing.T) {
+		filePath := fmt.Sprintf("%s/test/weirdbins/%s", workingDirectory, "zero_elf_palignment")
+		if _, err := os.Stat(filePath); errors.Is(err, os.ErrNotExist) {
+			t.Errorf("Test file %s doesn't exist\n", filePath)
+			return
+		}
+
+		_, err := main_impl(filePath, true, true, true, 0, "")
+		if err == nil {
+			t.Errorf("GoReSym found pclntab in a non-go binary, this is not possible.")
+		}
+	})
 }
 
 func TestBig(t *testing.T) {