dlfcn: dlerror needs to call free from the base namespace [BZ #24773]

Calling free directly may end up freeing a pointer allocated by the
dynamic loader using malloc from libc.so in the base namespace using
the allocator from libc.so in a secondary namespace, which results in
crashes.

This commit redirects the free call through GLRO and the dynamic
linker, to reach the correct namespace.  It also cleans up the dlerror
handling along the way, so that pthread_setspecific is no longer
needed (which avoids triggering bug 24774).

1 files changed, 23 insertions, 6 deletions

diff --git a/elf/tst-dlmopen-dlerror-mod.c b/elf/tst-dlmopen-dlerror-mod.c
index 7e95dcdeac..051025d3fa 100644
--- a/elf/tst-dlmopen-dlerror-mod.c
+++ b/elf/tst-dlmopen-dlerror-mod.c
@@ -18,6 +18,8 @@
 
 #include <dlfcn.h>
 #include <stddef.h>
+#include <stdio.h>
+#include <string.h>
 #include <support/check.h>
 
 /* Note: This object is not linked into the main program, so we cannot
@@ -25,17 +27,32 @@
    to use FAIL_EXIT1 (or something else that calls exit).  */
 
 void
-call_dlsym (void)
+call_dlsym (const char *name)
 {
-  void *ptr = dlsym (NULL, "does not exist");
+  void *ptr = dlsym (NULL, name);
   if (ptr != NULL)
-    FAIL_EXIT1 ("dlsym did not fail as expected");
+    FAIL_EXIT1 ("dlsym did not fail as expected for: %s", name);
+  const char *message = dlerror ();
+  if (strstr (message, ": undefined symbol: does not exist X") == NULL)
+    FAIL_EXIT1 ("invalid dlsym error message for [[%s]]: %s", name, message);
+  message = dlerror ();
+  if (message != NULL)
+    FAIL_EXIT1 ("second dlsym for [[%s]]: %s", name, message);
 }
 
 void
-call_dlopen (void)
+call_dlopen (const char *name)
 {
-  void *handle = dlopen ("tst-dlmopen-dlerror does not exist", RTLD_NOW);
+  void *handle = dlopen (name, RTLD_NOW);
   if (handle != NULL)
-    FAIL_EXIT1 ("dlopen did not fail as expected");
+    FAIL_EXIT1 ("dlopen did not fail as expected for: %s", name);
+  const char *message = dlerror ();
+  if (strstr (message, "X: cannot open shared object file:"
+              " No such file or directory") == NULL
+      && strstr (message, "X: cannot open shared object file:"
+                 " File name too long") == NULL)
+    FAIL_EXIT1 ("invalid dlopen error message for [[%s]]: %s", name, message);
+  message = dlerror ();
+  if (message != NULL)
+    FAIL_EXIT1 ("second dlopen for [[%s]]: %s", name, message);
 }