ldso_tls: Refetch dtv from memory if THREAD_DTV has changed

_dl_update_slotinfo might change THREAD_DTV () (if it needs to reallocate it),
but the caller (__tls_get_addr) doesn't refetch dtv from memory, it uses its
cached copy. This may crash (if dtv[GET_ADDR_MODULE] is off the cliff, or
might read uninitialized memory and return it.
Typically dtv[GET_ADDR_MODULE].pointer.val is NULL and so __tls_get_addr
returns NULL + offset_within_PT_TLS. The next time __tls_get_addr is called
for the same library it will return correct address as _dl_update_slotinfo
won't need to be called.

Signed-off-by: Jakub Jelinek <jakub@redhat.com>
Signed-off-by: Filippo Arcidiacono <filippo.arcidiacono@st.com>
Signed-off-by: Carmelo Amoroso <carmelo.amoroso@st.com>

1 files changed, 38 insertions, 0 deletions

diff --git a/test/tls/tst-tls18.c b/test/tls/tst-tls18.c
new file mode 100644
index 000000000..00dcdff4e
--- /dev/null
+++ b/test/tls/tst-tls18.c
@@ -0,0 +1,38 @@
+#include <dlfcn.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+static int
+do_test (void)
+{
+  char modname[sizeof "tst-tlsmod18aXX.so"];
+  void *h[20];
+  for (int i = 0; i < 20; i++)
+    {
+      snprintf (modname, sizeof modname, "tst-tlsmod18a%d.so", i);
+      h[i] = dlopen (modname, RTLD_LAZY);
+      if (h[i] == NULL)
+	{
+	  printf ("unexpectedly failed to open %s", modname);
+	  exit (1);
+	}
+    }
+
+  for (int i = 0; i < 20; i++)
+    {
+      int (*fp) (void) = (int (*) (void)) dlsym (h[i], "test");
+      if (fp == NULL)
+	{
+	  printf ("cannot find test in tst-tlsmod18a%d.so", i);
+	  exit (1);
+	}
+
+      if (fp ())
+	exit (1);
+    }
+
+  return 0;
+}
+
+#define TEST_FUNCTION do_test ()
+#include "../test-skeleton.c"