elf: Initialize GLRO (dl_read_only_area) after static dlopen (bug 33139)

The _dl_read_only_area function in the uninitialized ld.so after
static dlopen is not able to find anything.  Instead, we need to
redirect to the code from the statically linked main program.

Fixes commit d60fffe28a46b2a41fc308c1804ff02375d27408 ("debug:
Improve '%n' fortify detection (BZ 30932)").

Reviewed-by: Adhemerval Zanella Netto  <adhemerval.zanella@linaro.org>

debug/Makefile

@@ -184,12 +184,19 @@ CPPFLAGS-tst-chk-cancel.c += $(no-fortify-source) -D_FORTIFY_SOURCE=2
 CFLAGS-tst-sprintf-fortify-rdonly.c += $(no-fortify-source) -D_FORTIFY_SOURCE=2
 CFLAGS-tst-sprintf-fortify-rdonly-mod.c += $(no-fortify-source) -D_FORTIFY_SOURCE=2
 CFLAGS-tst-sprintf-fortify-rdonly-dlopen.c += $(no-fortify-source) -D_FORTIFY_SOURCE=2
+CFLAGS-tst-sprintf-fortify-rdonly-static.c += $(no-fortify-source) -D_FORTIFY_SOURCE=2
 CFLAGS-tst-fortify-syslog.c += $(no-fortify-source) -D_FORTIFY_SOURCE=2
 CFLAGS-tst-fortify-wide.c += $(no-fortify-source) -D_FORTIFY_SOURCE=2
 
 $(objpfx)tst-sprintf-fortify-rdonly: $(objpfx)tst-sprintf-fortify-rdonly-mod.so
 $(objpfx)tst-sprintf-fortify-rdonly.out: \
   $(objpfx)tst-sprintf-fortify-rdonly-dlopen.so
+$(objpfx)tst-sprintf-fortify-rdonly-static: \
+  $(objpfx)tst-sprintf-fortify-rdonly-dlopen.o
+$(objpfx)tst-sprintf-fortify-rdonly-static.out: \
+  $(objpfx)tst-sprintf-fortify-rdonly-dlopen.so
+tst-sprintf-fortify-rdonly-static-ENV = \
+  LD_LIBRARY_PATH=$(objpfx):$(common-objpfx):$(common-objpfx)/elf
 
 # _FORTIFY_SOURCE tests.
 # Auto-generate tests for _FORTIFY_SOURCE for different levels, compilers and
@@ -328,9 +335,14 @@ tests = \
   tst-longjmp_chk3 \
   tst-realpath-chk \
   tst-sprintf-fortify-rdonly \
+  tst-sprintf-fortify-rdonly-static \
   tst-sprintf-fortify-unchecked \
   # tests
 
+tests-static = \
+  tst-sprintf-fortify-rdonly-static \
+  # tests-static
+
 tests-time64 += \
   $(tests-all-time64-chk) \
   # tests-time64

debug/tst-sprintf-fortify-rdonly-static.c

@@ -0,0 +1 @@
+#include "tst-sprintf-fortify-rdonly.c"

elf/rtld.c

@@ -371,7 +371,6 @@ struct rtld_global_ro _rtld_global_ro attribute_relro =
     ._dl_error_free = _dl_error_free,
     ._dl_tls_get_addr_soft = _dl_tls_get_addr_soft,
     ._dl_libc_freeres = __rtld_libc_freeres,
-    ._dl_readonly_area = _dl_readonly_area,
   };
 /* If we would use strong_alias here the compiler would see a
    non-hidden definition.  This would undo the effect of the previous
@@ -458,6 +457,7 @@ _dl_start_final (void *arg, struct dl_start_final_info *info)
   /* Do not use an initializer for these members because it would
      interfere with __rtld_static_init.  */
   GLRO (dl_find_object) = &_dl_find_object;
+  GLRO (dl_readonly_area) = &_dl_readonly_area;
 
   /* If it hasn't happen yet record the startup time.  */
   rtld_timer_start (&start_time);

elf/rtld_static_init.c

@@ -79,6 +79,7 @@ __rtld_static_init (struct link_map *map)
     attribute_hidden;
   dl->_dl_tls_static_size = _dl_tls_static_size;
   dl->_dl_find_object = _dl_find_object;
+  dl->_dl_readonly_area = _dl_readonly_area;
 
   __rtld_static_init_arch (map, dl);
 }