[glibc/maskray/lld] x86: Check IFUNC definition in unrelocated executable [BZ #20019]

[glibc/maskray/lld] x86: Check IFUNC definition in unrelocated executable [BZ #20019]

[Fangrui Song]

https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=6ea5b57afa5cdc9ce367d2b69a2cebfb273e4617

commit 6ea5b57afa5cdc9ce367d2b69a2cebfb273e4617
Author: H.J. Lu <hjl.tools@gmail.com>
Date:   Mon Dec 28 05:28:49 2020 -0800

    x86: Check IFUNC definition in unrelocated executable [BZ #20019]
    
    Calling an IFUNC function defined in unrelocated executable also leads to
    segfault.  Issue a fatal error message when calling IFUNC function defined
    in the unrelocated executable from a shared library.

Diff:
---
 sysdeps/i386/dl-machine.h   | 16 +++++++++++-----
 sysdeps/x86_64/dl-machine.h | 16 +++++++++++-----
 2 files changed, 22 insertions(+), 10 deletions(-)

diff --git a/sysdeps/i386/dl-machine.h b/sysdeps/i386/dl-machine.h
index 50960605e6..23e9cc3bfb 100644
--- a/sysdeps/i386/dl-machine.h
+++ b/sysdeps/i386/dl-machine.h
@@ -337,16 +337,22 @@ 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_fatal_printf ("\
+%s: IFUNC symbol '%s' referenced in '%s' is defined in the executable \
+and creates an unsatisfiable circular dependency.\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 f582be5320..103eee6c3f 100644
--- a/sysdeps/x86_64/dl-machine.h
+++ b/sysdeps/x86_64/dl-machine.h
@@ -314,16 +314,22 @@ 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_fatal_printf ("\
+%s: IFUNC symbol '%s' referenced in '%s' is defined in the executable \
+and creates an unsatisfiable circular dependency.\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) ();