libio: Disable vtable validation for pre-2.1 interposed handles [BZ #25203]

Commit c402355dfa7807b8e0adb27c009135a7e2b9f1b0 ("libio: Disable
vtable validation in case of interposition [BZ #23313]") only covered
the interposable glibc 2.1 handles, in libio/stdfiles.c.  The
parallel code in libio/oldstdfiles.c needs similar detection logic.

Fixes (again) commit db3476aff19b75c4fdefbe65fcd5f0a90588ba51
("libio: Implement vtable verification [BZ #20191]").

Change-Id: Ief6f9f17e91d1f7263421c56a7dc018f4f595c21

diff --git a/libio/oldstdfiles.c b/libio/oldstdfiles.c
index bb1705b7b26995958d491b65a044d47efea0c85b..95c041a63286aebb6d26d65d18a78edcc73986b9 100644 (file)
--- a/libio/oldstdfiles.c
+++ b/libio/oldstdfiles.c
@@ -83,6 +83,11 @@ _IO_check_libio (void)
        = stderr->_vtable_offset =
        ((int) sizeof (struct _IO_FILE)
         - (int) sizeof (struct _IO_FILE_complete));
+
+      if (_IO_stdin_.vtable != &_IO_old_file_jumps
+         || _IO_stdout_.vtable != &_IO_old_file_jumps
+         || _IO_stderr_.vtable != &_IO_old_file_jumps)
+       IO_set_accept_foreign_vtables (&_IO_vtable_check);
     }
 }