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authorMao, Bibo <bibo.mao@intel.com>2005-12-12 00:37:00 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2005-12-12 08:57:41 -0800
commitb3e55c727ff7349c5db722fbdb8d99a151e8e0bf (patch)
tree90d437e565082afe25d68e530e793faeab4b49ac
parent3fe968f167975d10c639f03c4934f05a29da73c0 (diff)
[PATCH] Kprobes: Reference count the modules when probed on it
When a Kprobes are inserted/removed on a modules, the modules must be ref counted so as not to allow to unload while probes are registered on that module. Without this patch, the probed module is free to unload, and when the probing module unregister the probe, the kpobes code while trying to replace the original instruction might crash. Signed-off-by: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com> Signed-off-by: Mao Bibo <bibo.mao@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
-rw-r--r--kernel/kprobes.c18
1 files changed, 16 insertions, 2 deletions
diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 5beda378cc75..fde5a16a2913 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -462,9 +462,16 @@ int __kprobes register_kprobe(struct kprobe *p)
int ret = 0;
unsigned long flags = 0;
struct kprobe *old_p;
+ struct module *mod;
+
+ if ((!kernel_text_address((unsigned long) p->addr)) ||
+ in_kprobes_functions((unsigned long) p->addr))
+ return -EINVAL;
+
+ if ((mod = module_text_address((unsigned long) p->addr)) &&
+ (unlikely(!try_module_get(mod))))
+ return -EINVAL;
- if ((ret = in_kprobes_functions((unsigned long) p->addr)) != 0)
- return ret;
if ((ret = arch_prepare_kprobe(p)) != 0)
goto rm_kprobe;
@@ -488,6 +495,8 @@ out:
rm_kprobe:
if (ret == -EEXIST)
arch_remove_kprobe(p);
+ if (ret && mod)
+ module_put(mod);
return ret;
}
@@ -495,6 +504,7 @@ void __kprobes unregister_kprobe(struct kprobe *p)
{
unsigned long flags;
struct kprobe *old_p;
+ struct module *mod;
spin_lock_irqsave(&kprobe_lock, flags);
old_p = get_kprobe(p->addr);
@@ -506,6 +516,10 @@ void __kprobes unregister_kprobe(struct kprobe *p)
cleanup_kprobe(p, flags);
synchronize_sched();
+
+ if ((mod = module_text_address((unsigned long)p->addr)))
+ module_put(mod);
+
if (old_p->pre_handler == aggr_pre_handler &&
list_empty(&old_p->list))
kfree(old_p);