fix: incorrect conversion between integer types (#2605)

* chore: match strconv.ParseInt to file mode type

if a string is parsed into an int using strconv.Atoi,
and subsequently that int is converted into another integer type of a smaller size,
the result can produce unexpected values.
---------
Signed-off-by: Christopher Phillips <christopher.phillips@anchore.com>

syft/format/syftjson/to_syft_model.go

@@ -2,6 +2,8 @@ package syftjson
 
 import (
 	"fmt"
+	"io/fs"
+	"math"
 	"os"
 	"path"
 	"strconv"
@@ -76,14 +78,12 @@ func toSyftFiles(files []model.File) sbom.Artifacts {
 	for _, f := range files {
 		coord := f.Location
 		if f.Metadata != nil {
-			mode, err := strconv.ParseInt(strconv.Itoa(f.Metadata.Mode), 8, 64)
+			fm, err := safeFileModeConvert(f.Metadata.Mode)
 			if err != nil {
 				log.Warnf("invalid mode found in file catalog @ location=%+v mode=%q: %+v", coord, f.Metadata.Mode, err)
-				mode = 0
+				fm = 0
 			}
 
-			fm := os.FileMode(mode)
-
 			ret.FileMetadata[coord] = file.Metadata{
 				FileInfo: stereoscopeFile.ManualInfo{
 					NameValue: path.Base(coord.RealPath),
@@ -135,6 +135,20 @@ func toSyftFiles(files []model.File) sbom.Artifacts {
 	return ret
 }
 
+func safeFileModeConvert(val int) (fs.FileMode, error) {
+	if val < math.MinInt32 || val > math.MaxInt32 {
+		// Value is out of the range that int32 can represent
+		return 0, fmt.Errorf("value %d is out of the range that int32 can represent", val)
+	}
+
+	// Safe to convert to os.FileMode
+	mode, err := strconv.ParseInt(strconv.Itoa(val), 8, 64)
+	if err != nil {
+		return 0, err
+	}
+	return os.FileMode(mode), nil
+}
+
 func toSyftLicenses(m []model.License) (p []pkg.License) {
 	for _, l := range m {
 		p = append(p, pkg.License{

syft/format/syftjson/to_syft_model_test.go

@@ -2,6 +2,9 @@ package syftjson
 
 import (
 	"errors"
+	"io/fs"
+	"math"
+	"os"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
@@ -471,3 +474,45 @@ func Test_deduplicateErrors(t *testing.T) {
 		})
 	}
 }
+
+func Test_safeFileModeConvert(t *testing.T) {
+	tests := []struct {
+		name    string
+		val     int
+		want    fs.FileMode
+		wantErr bool
+	}{
+		{
+			// fs.go ModePerm 511 = FileMode = 0777 // Unix permission bits :192
+			name:    "valid perm",
+			val:     777,
+			want:    os.FileMode(511), // 777 in octal equals 511 in decimal
+			wantErr: false,
+		},
+		{
+			name:    "outside int32 high",
+			val:     int(math.MaxInt32) + 1,
+			want:    0,
+			wantErr: true,
+		},
+		{
+			name:    "outside int32 low",
+			val:     int(math.MinInt32) - 1,
+			want:    0,
+			wantErr: true,
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := safeFileModeConvert(tt.val)
+			if tt.wantErr {
+				assert.Error(t, err)
+				assert.Equal(t, tt.want, got)
+				return
+			}
+			assert.NoError(t, err)
+			assert.Equal(t, tt.want, got)
+		})
+	}
+}