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, 3 insertions, 7 deletions

diff --git a/malloc/set-freeres.c b/malloc/set-freeres.c
index 817fbea8b8..d404250151 100644
--- a/malloc/set-freeres.c
+++ b/malloc/set-freeres.c
@@ -20,6 +20,7 @@
 #include <set-hooks.h>
 #include <libc-internal.h>
 #include <unwind-link.h>
+#include <dlfcn/dlerror.h>
 
 #include "../nss/nsswitch.h"
 #include "../libio/libioP.h"
@@ -28,8 +29,6 @@ DEFINE_HOOK (__libc_subfreeres, (void));
 
 symbol_set_define (__libc_freeres_ptrs);
 
-extern __attribute__ ((weak)) void __libdl_freeres (void);
-
 extern __attribute__ ((weak)) void __libpthread_freeres (void);
 
 void __libc_freeres_fn_section
@@ -52,11 +51,6 @@ __libc_freeres (void)
       /* We run the resource freeing after IO cleanup.  */
       RUN_HOOK (__libc_subfreeres, ());
 
-      /* Call the libdl list of cleanup functions
-	 (weak-ref-and-check).  */
-      if (&__libdl_freeres != NULL)
-	__libdl_freeres ();
-
       /* Call the libpthread list of cleanup functions
 	 (weak-ref-and-check).  */
       if (&__libpthread_freeres != NULL)
@@ -66,6 +60,8 @@ __libc_freeres (void)
       __libc_unwind_link_freeres ();
 #endif
 
+      call_function_static_weak (__libc_dlerror_result_free);
+
       for (p = symbol_set_first_element (__libc_freeres_ptrs);
            !symbol_set_end_p (__libc_freeres_ptrs, p); ++p)
         free (*p);