Messages in this thread Patch in this message |  | | | Date | Tue, 04 Nov 2008 13:56:21 +0800 | | From | Lai Jiangshan <> | | Subject | [PATCH] kprobes: disable preempt for module_text_address() | |
__register_kprobe() may be preempted after module_text_address()
but before try_module_get(), and in this interval the module may be
unloaded and try_module_get(probed_mod) will access to invalid address.
this patch uses preempt_disable() to protect it.
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 8b57a25..8238ec5 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -622,6 +622,7 @@ static int __kprobes __register_kprobe(struct kprobe *p,
/*
* Check if are we probing a module.
*/
+ preempt_disable();
probed_mod = module_text_address((unsigned long) p->addr);
if (probed_mod) {
struct module *calling_mod = module_text_address(called_from);
@@ -631,12 +632,15 @@ static int __kprobes __register_kprobe(struct kprobe *p,
* unloading of self probing modules.
*/
if (calling_mod && calling_mod != probed_mod) {
- if (unlikely(!try_module_get(probed_mod)))
+ if (unlikely(!try_module_get(probed_mod))) {
+ preempt_enable();
return -EINVAL;
+ }
p->mod_refcounted = 1;
} else
probed_mod = NULL;
}
+ preempt_enable();
p->nmissed = 0;
INIT_LIST_HEAD(&p->list);
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