debug/macho: use saferio to read dynamic indirect symbols

No test case because the problem can only happen for invalid data. Let
the fuzzer find cases like this.

For #47653
Fixes #58755

Change-Id: I5b95a21f47ec306ad90cd6221f0566c6f8b6c3ad
Reviewed-on: https://go-review.googlesource.com/c/go/+/471835
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>

Author: ianlancetaylor

src/debug/macho/file.go

@@ -361,8 +361,8 @@ func NewFile(r io.ReaderAt) (*File, error) {
 					"number of undefined symbols after index in dynamic symbol table command is greater than symbol table length (%d > %d)",
 					hdr.Iundefsym+hdr.Nundefsym, len(f.Symtab.Syms)), nil}
 			}
-			dat := make([]byte, hdr.Nindirectsyms*4)
-			if _, err := r.ReadAt(dat, int64(hdr.Indirectsymoff)); err != nil {
+			dat, err := saferio.ReadDataAt(r, uint64(hdr.Nindirectsyms)*4, int64(hdr.Indirectsymoff))
+			if err != nil {
 				return nil, err
 			}
 			x := make([]uint32, hdr.Nindirectsyms)