[PATCH] x86: Check IFUNC definition in unrelocated executable [BZ #20019]

[H.J. Lu]

Calling an IFUNC function defined in unrelocated executable may also
lead to segfault.  Issue an error message when calling IFUNC function
defined in the unrelocated executable from a shared library.
---
 sysdeps/i386/dl-machine.h   | 15 ++++++++++-----
 sysdeps/x86_64/dl-machine.h | 15 ++++++++++-----
 2 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
index fea9e579ec..dedda484ba 100644
--- a/sysdeps/i386/dl-machine.h
+++ b/sysdeps/i386/dl-machine.h
@@ -337,16 +337,21 @@ elf_machine_rel (struct link_map *map, const Elf32_Rel *reloc,
 	{
 # ifndef RTLD_BOOTSTRAP
 	  if (sym_map != map
-	      && sym_map->l_type != lt_executable
 	      && !sym_map->l_relocated)
 	    {
 	      const char *strtab
 		= (const char *) D_PTR (map, l_info[DT_STRTAB]);
-	      _dl_error_printf ("\
+	      if (sym_map->l_type == lt_executable)
+		_dl_error_printf ("\
+%s: IFUNC symbol `%s' referenced in `%s' is defined in executable\n",
+				  RTLD_PROGNAME, strtab + refsym->st_name,
+				  map->l_name);
+	      else
+		_dl_error_printf ("\
 %s: Relink `%s' with `%s' for IFUNC symbol `%s'\n",
-				RTLD_PROGNAME, map->l_name,
-				sym_map->l_name,
-				strtab + refsym->st_name);
+				  RTLD_PROGNAME, map->l_name,
+				  sym_map->l_name,
+				  strtab + refsym->st_name);
 	    }
 # endif
 	  value = ((Elf32_Addr (*) (void)) value) ();
diff --git a/sysdeps/x86_64/dl-machine.h b/sysdeps/x86_64/dl-machine.h
index bb93c7c6ab..fc847f4bc2 100644
--- a/sysdeps/x86_64/dl-machine.h
+++ b/sysdeps/x86_64/dl-machine.h
@@ -314,16 +314,21 @@ elf_machine_rela (struct link_map *map, const ElfW(Rela) *reloc,
 	{
 # ifndef RTLD_BOOTSTRAP
 	  if (sym_map != map
-	      && sym_map->l_type != lt_executable
 	      && !sym_map->l_relocated)
 	    {
 	      const char *strtab
 		= (const char *) D_PTR (map, l_info[DT_STRTAB]);
-	      _dl_error_printf ("\
+	      if (sym_map->l_type == lt_executable)
+		_dl_error_printf ("\
+%s: IFUNC symbol `%s' referenced in `%s' is defined in executable\n",
+				  RTLD_PROGNAME, strtab + refsym->st_name,
+				  map->l_name);
+	      else
+		_dl_error_printf ("\
 %s: Relink `%s' with `%s' for IFUNC symbol `%s'\n",
-				RTLD_PROGNAME, map->l_name,
-				sym_map->l_name,
-				strtab + refsym->st_name);
+				  RTLD_PROGNAME, map->l_name,
+				  sym_map->l_name,
+				  strtab + refsym->st_name);
 	    }
 # endif
 	  value = ((ElfW(Addr) (*) (void)) value) ();
-- 
2.29.2