Avoid crashing in LD_DEBUG when program name is unavailable

Resolves: #15465

The program name may be unavailable if the user application tampers
with argc and argv[].  Some parts of the dynamic linker caters for
this while others don't, so this patch consolidates the check and
fallback into a single macro and updates all users.

14 files changed, 92 insertions, 49 deletions

diff --git a/elf/Makefile b/elf/Makefile
index c01ca9e..6f40414 100644
--- a/elf/Makefile
+++ b/elf/Makefile
@@ -145,7 +145,7 @@ tests += loadtest restest1 preloadtest loadfail multiload origtest resolvfail \
 	 tst-audit1 tst-audit2 tst-audit8 \
 	 tst-stackguard1 tst-addr1 tst-thrlock \
 	 tst-unique1 tst-unique2 tst-unique3 tst-unique4 \
-	 tst-initorder tst-initorder2 tst-relsort1
+	 tst-initorder tst-initorder2 tst-relsort1 tst-null-argv
 #	 reldep9
 test-srcs = tst-pathopt
 selinux-enabled := $(shell cat /selinux/enforce 2> /dev/null)
@@ -208,7 +208,7 @@ modules-names = testobj1 testobj2 testobj3 testobj4 testobj5 testobj6 \
 		tst-initorder2a tst-initorder2b tst-initorder2c \
 		tst-initorder2d \
 		tst-relsort1mod1 tst-relsort1mod2 tst-array2dep \
-		tst-array5dep
+		tst-array5dep tst-null-argv-lib
 ifeq (yesyes,$(have-fpie)$(build-shared))
 modules-names += tst-piemod1
 tests += tst-pie1
@@ -494,7 +494,9 @@ $(objpfx)tst-initorderb2.so: $(objpfx)tst-initorderb1.so $(objpfx)tst-initordera
 $(objpfx)tst-initordera3.so: $(objpfx)tst-initorderb2.so $(objpfx)tst-initorderb1.so
 $(objpfx)tst-initordera4.so: $(objpfx)tst-initordera3.so
 $(objpfx)tst-initorder: $(objpfx)tst-initordera4.so $(objpfx)tst-initordera1.so $(objpfx)tst-initorderb2.so
+$(objpfx)tst-null-argv: $(objpfx)tst-null-argv-lib.so
 
+tst-null-argv-ENV = LD_DEBUG=all LD_DEBUG_OUTPUT=$(objpfx)tst-null-argv.debug.out
 LDFLAGS-nodel2mod3.so = $(no-as-needed)
 LDFLAGS-reldepmod5.so = $(no-as-needed)
 LDFLAGS-reldep6mod1.so = $(no-as-needed)
diff --git a/elf/dl-conflict.c b/elf/dl-conflict.c
index d63086d..11e3cd8 100644
--- a/elf/dl-conflict.c
+++ b/elf/dl-conflict.c
@@ -33,8 +33,7 @@ _dl_resolve_conflicts (struct link_map *l, ElfW(Rela) *conflict,
 {
 #if ! ELF_MACHINE_NO_RELA
   if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_RELOC, 0))
-    _dl_debug_printf ("\nconflict processing: %s\n",
-		      l->l_name[0] ? l->l_name : rtld_progname);
+    _dl_debug_printf ("\nconflict processing: %s\n", DSO_FILENAME (l->l_name));
 
   {
     /* Do the conflict relocation of the object and library GOT and other
diff --git a/elf/dl-deps.c b/elf/dl-deps.c
index cd1c236..1c36f50 100644
--- a/elf/dl-deps.c
+++ b/elf/dl-deps.c
@@ -310,8 +310,7 @@ _dl_map_object_deps (struct link_map *map,
 		      _dl_debug_printf ("load auxiliary object=%s"
 					" requested by file=%s\n",
 					name,
-					l->l_name[0]
-					? l->l_name : rtld_progname);
+					DSO_FILENAME (l->l_name));
 
 		    /* We must be prepared that the addressed shared
 		       object is not available.  */
@@ -337,8 +336,7 @@ _dl_map_object_deps (struct link_map *map,
 		      _dl_debug_printf ("load filtered object=%s"
 					" requested by file=%s\n",
 					name,
-					l->l_name[0]
-					? l->l_name : rtld_progname);
+					DSO_FILENAME (l->l_name));
 
 		    /* For filter objects the dependency must be available.  */
 		    bool malloced;
diff --git a/elf/dl-error.c b/elf/dl-error.c
index 7987845..8257c17 100644
--- a/elf/dl-error.c
+++ b/elf/dl-error.c
@@ -119,7 +119,7 @@ _dl_signal_error (int errcode, const char *objname, const char *occation,
       /* Lossage while resolving the program's own symbols is always fatal.  */
       char buffer[1024];
       _dl_fatal_printf ("%s: %s: %s%s%s%s%s\n",
-			rtld_progname ?: "<program name unknown>",
+			RTLD_PROGNAME,
 			occation ?: N_("error while loading shared libraries"),
 			objname, *objname ? ": " : "",
 			errstring, errcode ? ": " : "",
diff --git a/elf/dl-fini.c b/elf/dl-fini.c
index c5d1674..6b245f0 100644
--- a/elf/dl-fini.c
+++ b/elf/dl-fini.c
@@ -237,7 +237,7 @@ _dl_fini (void)
 		  if (__builtin_expect (GLRO(dl_debug_mask)
 					& DL_DEBUG_IMPCALLS, 0))
 		    _dl_debug_printf ("\ncalling fini: %s [%lu]\n\n",
-				      l->l_name[0] ? l->l_name : rtld_progname,
+				      DSO_FILENAME (l->l_name),
 				      ns);
 
 		  /* First see whether an array is given.  */
diff --git a/elf/dl-init.c b/elf/dl-init.c
index fe4d2a0..a657eb6 100644
--- a/elf/dl-init.c
+++ b/elf/dl-init.c
@@ -54,7 +54,7 @@ call_init (struct link_map *l, int argc, char **argv, char **env)
   /* Print a debug message if wanted.  */
   if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
     _dl_debug_printf ("\ncalling init: %s\n\n",
-		      l->l_name[0] ? l->l_name : rtld_progname);
+		      DSO_FILENAME (l->l_name));
 
   /* Now run the local constructors.  There are two forms of them:
      - the one named by DT_INIT
@@ -110,8 +110,7 @@ _dl_init (struct link_map *main_map, int argc, char **argv, char **env)
 
       if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_IMPCALLS, 0))
 	_dl_debug_printf ("\ncalling preinit: %s\n\n",
-			  main_map->l_name[0]
-			  ? main_map->l_name : rtld_progname);
+			  DSO_FILENAME (main_map->l_name));
 
       addrs = (ElfW(Addr) *) (preinit_array->d_un.d_ptr + main_map->l_addr);
       for (cnt = 0; cnt < i; ++cnt)
diff --git a/elf/dl-load.c b/elf/dl-load.c
index dd182c9..757b6ec 100644
--- a/elf/dl-load.c
+++ b/elf/dl-load.c
@@ -1651,7 +1651,7 @@ print_search_path (struct r_search_path_elem **list,
 
   if (name != NULL)
     _dl_debug_printf_c ("\t\t(%s from file %s)\n", what,
-			name[0] ? name : rtld_progname);
+			DSO_FILENAME (name));
   else
     _dl_debug_printf_c ("\t\t(%s)\n", what);
 }
@@ -2124,8 +2124,7 @@ _dl_map_object (struct link_map *loader, const char *name,
     _dl_debug_printf ((mode & __RTLD_CALLMAP) == 0
 		      ? "\nfile=%s [%lu];  needed by %s [%lu]\n"
 		      : "\nfile=%s [%lu];  dynamically loaded by %s [%lu]\n",
-		      name, nsid, loader->l_name[0]
-		      ? loader->l_name : rtld_progname, loader->l_ns);
+		      name, nsid, DSO_FILENAME (loader->l_name), loader->l_ns);
 
 #ifdef SHARED
   /* Give the auditing libraries a chance to change the name before we
diff --git a/elf/dl-lookup.c b/elf/dl-lookup.c
index 68f8dac..39f463e 100644
--- a/elf/dl-lookup.c
+++ b/elf/dl-lookup.c
@@ -112,8 +112,7 @@ do_lookup_x (const char *undef_name, uint_fast32_t new_hash,
       /* Print some debugging info if wanted.  */
       if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_SYMBOLS, 0))
 	_dl_debug_printf ("symbol=%s;  lookup in file=%s [%lu]\n",
-			  undef_name,
-			  map->l_name[0] ? map->l_name : rtld_progname,
+			  undef_name, DSO_FILENAME (map->l_name),
 			  map->l_ns);
 
       /* If the hash table is empty there is nothing to do here.  */
@@ -667,10 +666,9 @@ add_dependency (struct link_map *undef_map, struct link_map *map, int flags)
       if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_FILES, 0))
 	_dl_debug_printf ("\
 \nfile=%s [%lu];  needed by %s [%lu] (relocation dependency)\n\n",
-			  map->l_name[0] ? map->l_name : rtld_progname,
+			  DSO_FILENAME (map->l_name),
 			  map->l_ns,
-			  undef_map->l_name[0]
-			  ? undef_map->l_name : rtld_progname,
+			  DSO_FILENAME (undef_map->l_name),
 			  undef_map->l_ns);
     }
   else
@@ -751,9 +749,7 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
 	  const char *reference_name = undef_map ? undef_map->l_name : NULL;
 
 	  /* XXX We cannot translate the message.  */
-	  _dl_signal_cerror (0, (reference_name[0]
-				 ? reference_name
-				 : (rtld_progname ?: "<main program>")),
+	  _dl_signal_cerror (0, DSO_FILENAME (reference_name),
 			     N_("relocation error"),
 			     make_string ("symbol ", undef_name, ", version ",
 					  version->name,
@@ -780,9 +776,7 @@ _dl_lookup_symbol_x (const char *undef_name, struct link_map *undef_map,
 				     ? version->name : "");
 
 	  /* XXX We cannot translate the message.  */
-	  _dl_signal_cerror (0, (reference_name[0]
-				 ? reference_name
-				 : (rtld_progname ?: "<main program>")),
+	  _dl_signal_cerror (0, DSO_FILENAME (reference_name),
 			     N_("symbol lookup error"),
 			     make_string (undefined_msg, undef_name,
 					  versionstr, versionname));
@@ -912,11 +906,9 @@ _dl_debug_bindings (const char *undef_name, struct link_map *undef_map,
   if (GLRO(dl_debug_mask) & DL_DEBUG_BINDINGS)
     {
       _dl_debug_printf ("binding file %s [%lu] to %s [%lu]: %s symbol `%s'",
-			(reference_name[0]
-			 ? reference_name
-			 : (rtld_progname ?: "<main program>")),
+			DSO_FILENAME (reference_name),
 			undef_map->l_ns,
-			value->m->l_name[0] ? value->m->l_name : rtld_progname,
+			DSO_FILENAME (value->m->l_name),
 			value->m->l_ns,
 			protected ? "protected" : "normal", undef_name);
       if (version)
diff --git a/elf/dl-open.c b/elf/dl-open.c
index 92fae7f..0f054bf 100644
--- a/elf/dl-open.c
+++ b/elf/dl-open.c
@@ -733,7 +733,7 @@ void
 _dl_show_scope (struct link_map *l, int from)
 {
   _dl_debug_printf ("object=%s [%lu]\n",
-		    *l->l_name ? l->l_name : rtld_progname, l->l_ns);
+		    DSO_FILENAME (l->l_name), l->l_ns);
   if (l->l_scope != NULL)
     for (int scope_cnt = from; l->l_scope[scope_cnt] != NULL; ++scope_cnt)
       {
@@ -744,7 +744,7 @@ _dl_show_scope (struct link_map *l, int from)
 	    _dl_debug_printf_c (" %s",
 				l->l_scope[scope_cnt]->r_list[cnt]->l_name);
 	  else
-	    _dl_debug_printf_c (" %s", rtld_progname);
+	    _dl_debug_printf_c (" %s", RTLD_PROGNAME);
 
 	_dl_debug_printf_c ("\n");
       }
diff --git a/elf/dl-reloc.c b/elf/dl-reloc.c
index 73d98f8..5c54310 100644
--- a/elf/dl-reloc.c
+++ b/elf/dl-reloc.c
@@ -185,8 +185,7 @@ _dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
 
   if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_RELOC, 0))
     _dl_debug_printf ("\nrelocation processing: %s%s\n",
-		      l->l_name[0] ? l->l_name : rtld_progname,
-		      lazy ? " (lazy)" : "");
+		      DSO_FILENAME (l->l_name), lazy ? " (lazy)" : "");
 
   /* DT_TEXTREL is now in level 2 and might phase out at some time.
      But we rewrite the DT_FLAGS entry to a DT_TEXTREL entry to make
@@ -276,7 +275,7 @@ _dl_relocate_object (struct link_map *l, struct r_scope_elem *scope[],
 	    errstring = N_("%s: no PLTREL found in object %s\n");
 	  fatal:
 	    _dl_fatal_printf (errstring,
-			      rtld_progname ?: "<program name unknown>",
+			      RTLD_PROGNAME,
 			      l->l_name);
 	  }
 
diff --git a/elf/dl-version.c b/elf/dl-version.c
index c02baa0..62be4ae 100644
--- a/elf/dl-version.c
+++ b/elf/dl-version.c
@@ -85,7 +85,7 @@ match_symbol (const char *name, Lmid_t ns, ElfW(Word) hash, const char *string,
   if (__builtin_expect (GLRO(dl_debug_mask) & DL_DEBUG_VERSIONS, 0))
     _dl_debug_printf ("\
 checking for version `%s' in file %s [%lu] required by file %s [%lu]\n",
-		      string, map->l_name[0] ? map->l_name : rtld_progname,
+		      string, DSO_FILENAME (map->l_name),
 		      map->l_ns, name, ns);
 
   if (__builtin_expect (map->l_info[VERSYMIDX (DT_VERDEF)] == NULL, 0))
@@ -162,7 +162,7 @@ no version information available (required by ", name, ")");
 			   name, ")");
   result = 1;
  call_cerror:
-  _dl_signal_cerror (0, map->l_name[0] ? map->l_name : rtld_progname,
+  _dl_signal_cerror (0, DSO_FILENAME (map->l_name),
 		     N_("version lookup error"), errstring);
   return result;
 }
@@ -210,7 +210,7 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode)
 					  &buf[sizeof (buf) - 1], 10, 0),
 				   " of Verneed record\n");
 	call_error:
-	  _dl_signal_error (errval, *map->l_name ? map->l_name : rtld_progname,
+	  _dl_signal_error (errval, DSO_FILENAME (map->l_name),
 			    NULL, errstring);
 	}
 
@@ -234,8 +234,7 @@ _dl_check_map_versions (struct link_map *map, int verbose, int trace_mode)
 	      while (1)
 		{
 		  /* Match the symbol.  */
-		  result |= match_symbol ((*map->l_name
-					   ? map->l_name : rtld_progname),
+		  result |= match_symbol (DSO_FILENAME (map->l_name),
 					  map->l_ns, aux->vna_hash,
 					  strtab + aux->vna_name,
 					  needed->l_real, verbose,
diff --git a/elf/rtld.c b/elf/rtld.c
index 23238ad..91da88c 100644
--- a/elf/rtld.c
+++ b/elf/rtld.c
@@ -1840,10 +1840,8 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
 	      if (_dl_name_match_p (GLRO(dl_trace_prelink), l))
 		GLRO(dl_trace_prelink_map) = l;
 	      _dl_printf ("\t%s => %s (0x%0*Zx, 0x%0*Zx)",
-			  l->l_libname->name[0] ? l->l_libname->name
-			  : rtld_progname ?: "<main program>",
-			  l->l_name[0] ? l->l_name
-			  : rtld_progname ?: "<main program>",
+			  DSO_FILENAME (l->l_libname->name),
+			  DSO_FILENAME (l->l_name),
 			  (int) sizeof l->l_map_start * 2,
 			  (size_t) l->l_map_start,
 			  (int) sizeof l->l_addr * 2,
@@ -2000,8 +1998,7 @@ ERROR: ld.so: object '%s' cannot be loaded as audit interface: %s; ignored.\n",
 		      first = 0;
 		    }
 
-		  _dl_printf ("\t%s:\n",
-			      map->l_name[0] ? map->l_name : rtld_progname);
+		  _dl_printf ("\t%s:\n", DSO_FILENAME (map->l_name));
 
 		  while (1)
 		    {
@@ -2324,7 +2321,7 @@ print_unresolved (int errcode __attribute__ ((unused)), const char *objname,
 		  const char *errstring)
 {
   if (objname[0] == '\0')
-    objname = rtld_progname ?: "<main program>";
+    objname = RTLD_PROGNAME;
   _dl_error_printf ("%s	(%s)\n", errstring, objname);
 }
 
@@ -2334,7 +2331,7 @@ static void
 print_missing_version (int errcode __attribute__ ((unused)),
 		       const char *objname, const char *errstring)
 {
-  _dl_error_printf ("%s: %s: %s\n", rtld_progname ?: "<program name unknown>",
+  _dl_error_printf ("%s: %s: %s\n", RTLD_PROGNAME,
 		    objname, errstring);
 }
 
diff --git a/elf/tst-null-argv-lib.c b/elf/tst-null-argv-lib.c
new file mode 100644
index 0000000..e754299
--- /dev/null
+++ b/elf/tst-null-argv-lib.c
@@ -0,0 +1,24 @@
+/* Verify that program does not crash when LD_DEBUG is set and the program name
+   is not available.  This is the library.
+   Copyright (C) 2013 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+void
+foo (void)
+{
+  return;
+}
diff --git a/elf/tst-null-argv.c b/elf/tst-null-argv.c
new file mode 100644
index 0000000..dc242e4
--- /dev/null
+++ b/elf/tst-null-argv.c
@@ -0,0 +1,35 @@
+/* Verify that program does not crash when LD_DEBUG is set and the program name
+   is not available.
+   Copyright (C) 2013 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+extern void foo (void);
+
+int
+do_test (int argc, char **argv)
+{
+  argv[0] = argv[1];
+  argc--;
+
+  /* This should result in a symbol lookup, causing a volley of debug output
+     when LD_DEBUG=symbols.  */
+  foo ();
+
+  return 0;
+}
+
+#include <test-skeleton.c>