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authorMasami Hiramatsu <mhiramat@redhat.com>2008-11-12 13:26:51 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2008-11-12 17:17:16 -0800
commita189d0350f387786b1fb5a5d19e3a5ab0bc0cceb (patch)
treed6133d035e0d23a8271f12204e53338f8f343351
parent3b1b3f6e57064aa8f91c290fe51cda4c74642902 (diff)
kprobes: disable preempt for module_text_address() and kernel_text_address()
__register_kprobe() can be preempted after checking probing address but before module_text_address() or try_module_get(), and in this interval the module can be unloaded. In that case, try_module_get(probed_mod) will access to invalid address, or kprobe will probe invalid address. This patch uses preempt_disable() to protect it and uses __module_text_address() and __kernel_text_address(). Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com> Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com> Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com> Cc: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--kernel/kprobes.c21
1 files changed, 16 insertions, 5 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 8b57a2597f2..f83c5e42fb0 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -613,30 +613,37 @@ static int __kprobes __register_kprobe(struct kprobe *p,
return -EINVAL;
p->addr = addr;
- if (!kernel_text_address((unsigned long) p->addr) ||
- in_kprobes_functions((unsigned long) p->addr))
+ preempt_disable();
+ if (!__kernel_text_address((unsigned long) p->addr) ||
+ in_kprobes_functions((unsigned long) p->addr)) {
+ preempt_enable();
return -EINVAL;
+ }
p->mod_refcounted = 0;
/*
* Check if are we probing a module.
*/
- probed_mod = module_text_address((unsigned long) p->addr);
+ probed_mod = __module_text_address((unsigned long) p->addr);
if (probed_mod) {
- struct module *calling_mod = module_text_address(called_from);
+ struct module *calling_mod;
+ calling_mod = __module_text_address(called_from);
/*
* We must allow modules to probe themself and in this case
* avoid incrementing the module refcount, so as to allow
* 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);
@@ -718,6 +725,10 @@ static void __kprobes __unregister_kprobe_bottom(struct kprobe *p)
struct kprobe *old_p;
if (p->mod_refcounted) {
+ /*
+ * Since we've already incremented refcount,
+ * we don't need to disable preemption.
+ */
mod = module_text_address((unsigned long)p->addr);
if (mod)
module_put(mod);