elf: Call __libc_early_init for reused namespaces (bug 29528)

libc_map is never reset to NULL, neither during dlclose nor on a
dlopen call which reuses the namespace structure.  As a result, if a
namespace is reused, its libc is not initialized properly.  The most
visible result is a crash in the <ctype.h> functions.

To prevent similar bugs on namespace reuse from surfacing,
unconditionally initialize the chosen namespace to zero using memset.

(cherry picked from commit d0e357ff45a75553dee3b17ed7d303bfa544f6fe)

1 files changed, 8 insertions, 5 deletions

diff --git a/elf/dl-open.c b/elf/dl-open.c
index 1b965457c4..08cf5a02ad 100644
--- a/elf/dl-open.c
+++ b/elf/dl-open.c
@@ -819,11 +819,14 @@ _dl_open (const char *file, int mode, const void *caller_dlopen, Lmid_t nsid,
 	  _dl_signal_error (EINVAL, file, NULL, N_("\
 no more namespaces available for dlmopen()"));
 	}
-      else if (nsid == GL(dl_nns))
-	{
-	  __rtld_lock_initialize (GL(dl_ns)[nsid]._ns_unique_sym_table.lock);
-	  ++GL(dl_nns);
-	}
+
+      if (nsid == GL(dl_nns))
+	++GL(dl_nns);
+
+      /* Initialize the new namespace.  Most members are
+	 zero-initialized, only the lock needs special treatment.  */
+      memset (&GL(dl_ns)[nsid], 0, sizeof (GL(dl_ns)[nsid]));
+      __rtld_lock_initialize (GL(dl_ns)[nsid]._ns_unique_sym_table.lock);
 
       _dl_debug_initialize (0, nsid)->r_state = RT_CONSISTENT;
     }