From: Masami Hiramatsu <mhiramat@redhat.com>
Date: Tue, 12 Aug 2008 12:13:40 -0400
Subject: [ia64] fix to check module_free parameter
Message-id: 48A1B6B4.9060209@redhat.com
O-Subject: [PATCH RHEL5] BZ457961: fix to check module_free() parameter on ia64
Bugzilla: 457961
RH-Acked-by: Prarit Bhargava <prarit@redhat.com>
RH-Acked-by: Luming Yu <luyu@redhat.com>
RH-Acked-by: Luming Yu <luyu@redhat.com>

This patch fixes a kernel crash bug on ia64.

Bugzilla:
https://bugzilla.redhat.com/show_bug.cgi?id=457961

Brew:
http://brewweb.devel.redhat.com/brew/taskinfo?taskID=1426895

Description:
 module_free() on ia64 refers the first parameter before checking.
 But it is called like below(in kernel/kprobes). The first parameter is always NULL.
This happens when many probe points(>1024) are set by kprobes.
I encountered this with using SystemTap. It can set many probes easily.

Test:
I tested systemtap script which is reported on the bugzilla on ia64 with
this patch, and ensured it was fixed.

Upstream:
740a8de0796dd12890b3c8ddcfabfcb528b78d40

Thank you,

diff --git a/arch/ia64/kernel/module.c b/arch/ia64/kernel/module.c
index 158e3c5..32e5e0a 100644
--- a/arch/ia64/kernel/module.c
+++ b/arch/ia64/kernel/module.c
@@ -321,7 +321,8 @@ module_alloc (unsigned long size)
 void
 module_free (struct module *mod, void *module_region)
 {
-	if (mod->arch.init_unw_table && module_region == mod->module_init) {
+	if (mod && mod->arch.init_unw_table &&
+	    module_region == mod->module_init) {
 		unw_remove_unwind_table(mod->arch.init_unw_table);
 		mod->arch.init_unw_table = NULL;
 	}