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[PATCH] elf: Assert that objects are relocated before their constructors run
- From: Florian Weimer <fweimer at redhat dot com>
- To: libc-alpha at sourceware dot org
- Date: Wed, 11 Sep 2019 11:57:24 +0200
- Subject: [PATCH] elf: Assert that objects are relocated before their constructors run
If we try to run constructors before relocation, this is always
a dynamic linker bug. An assert is easier to notice than a call
via an invalid function pointer (which may not even produce a valid
call stack).
2019-09-11 Florian Weimer <fweimer@redhat.com>
* elf/dl-init.c (call_init): Assert that the object has been
relocated.
diff --git a/elf/dl-init.c b/elf/dl-init.c
index 3721bca81e..a998992544 100644
--- a/elf/dl-init.c
+++ b/elf/dl-init.c
@@ -16,6 +16,7 @@
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
+#include <assert.h>
#include <stddef.h>
#include <ldsodefs.h>
@@ -27,6 +28,11 @@ typedef void (*init_t) (int, char **, char **);
static void
call_init (struct link_map *l, int argc, char **argv, char **env)
{
+ /* If the object has not been relocated, this is a bug. The
+ function pointers are invalid in this case. (Executables do not
+ need relocation, and neither do proxy objects.) */
+ assert (l->l_real->l_relocated || l->l_real->l_type == lt_executable);
+
if (l->l_init_called)
/* This object is all done. */
return;