Subject: Problem: CONFIG_KALLSYMS is not set + kernel/module.c

From: [email-masked] (Mark Hinds)
Date: Sun, 29 Jul 2012 08:27:17 -0700

In linux-3.2.xx I've been getting kernel dumps when I modprobe some
modules with CONFIG_KALLSYMS diabled - nls_base.ko for example.
I traced the problem to kernel/module.c, line 2607 or there about.

Starting with:
ptr = module_alloc_update_bounds(mod->init_size);

If mod->init_size == 0 then foobar happens. I assume that there is
no init section in some modules when CONFIG_KALLSYMS is disabled.

Here is my fix:

Index: kernel/module.c
===================================================================
--- kernel/module.c	(.../linux-3.2.24/kernel/module.c)	(revision 9084)
+++ kernel/module.c	(.../linux-3.2.24-ces/kernel/module.c)	(working copy)
@@ -2604,20 +2604,24 @@
  	memset(ptr, 0, mod->core_size);
  	mod->module_core = ptr;

-	ptr = module_alloc_update_bounds(mod->init_size);
-	/*
-	 * The pointer to this block is stored in the module structure
-	 * which is inside the block. This block doesn't need to be
-	 * scanned as it contains data and code that will be freed
-	 * after the module is initialized.
-	 */
-	kmemleak_ignore(ptr);
-	if (!ptr && mod->init_size) {
-		module_free(mod, mod->module_core);
-		return -ENOMEM;
+#warning ### CES/zoro fix problem with mod->init_size == 0
+	if (mod->init_size) {
+		ptr = module_alloc_update_bounds(mod->init_size);
+		/*
+	 	* The pointer to this block is stored in the module structure
+	 	* which is inside the block. This block doesn't need to be
+	 	* scanned as it contains data and code that will be freed
+	 	* after the module is initialized.
+	 	*/
+		kmemleak_ignore(ptr);
+		if (!ptr) {
+			module_free(mod, mod->module_core);
+			return -ENOMEM;
+		}
+		memset(ptr, 0, mod->init_size);
+		mod->module_init = ptr;
  	}
-	memset(ptr, 0, mod->init_size);
-	mod->module_init = ptr;
+	else mod->module_init = NULL;

  	/* Transfer each section which specifies SHF_ALLOC */
  	DEBUGP("final section addresses:\n");