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Commit 1f0ab409 authored by Ananth N Mavinakayanahalli's avatar Ananth N Mavinakayanahalli Committed by Frederic Weisbecker
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kprobes: Prevent re-registration of the same kprobe 



Prevent re-registration of the same kprobe. This situation, though
unlikely, needs to be flagged since it can lead to a system crash if
it's not handled.

The core change itself is small, but the helper routine needed to be
moved around a bit; hence the diffstat.

Signed-off-by: default avatarAnanth N <Mavinakayanahalli&lt;ananth@in.ibm.com>
Acked-by: default avatarMasami Hiramatsu <mhiramat@redhat.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Frank Ch. Eigler <fche@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Jason Baron <jbaron@redhat.com>
Cc: K.Prasad <prasad@linux.vnet.ibm.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <20090915051307.GB26458@in.ibm.com>
Signed-off-by: default avatarFrederic Weisbecker <fweisbec@gmail.com>
parent 5a0d9050

kernel/kprobes.c

+38 −20
Original line number Diff line number Diff line
@@ -676,6 +676,40 @@ static kprobe_opcode_t __kprobes *kprobe_addr(struct kprobe *p) 
	return (kprobe_opcode_t *)(((char *)addr) + p->offset);

}



/* Check passed kprobe is valid and return kprobe in kprobe_table. */

static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)

{

	struct kprobe *old_p, *list_p;



	old_p = get_kprobe(p->addr);

	if (unlikely(!old_p))

		return NULL;



	if (p != old_p) {

		list_for_each_entry_rcu(list_p, &old_p->list, list)

			if (list_p == p)

			/* kprobe p is a valid probe */

				goto valid;

		return NULL;

	}

valid:

	return old_p;

}



/* Return error if the kprobe is being re-registered */

static inline int check_kprobe_rereg(struct kprobe *p)

{

	int ret = 0;

	struct kprobe *old_p;



	mutex_lock(&kprobe_mutex);

	old_p = __get_valid_kprobe(p);

	if (old_p)

		ret = -EINVAL;

	mutex_unlock(&kprobe_mutex);

	return ret;

}



int __kprobes register_kprobe(struct kprobe *p)

{

	int ret = 0;
@@ -688,6 +722,10 @@ int __kprobes register_kprobe(struct kprobe *p) 
		return -EINVAL;

	p->addr = addr;



	ret = check_kprobe_rereg(p);

	if (ret)

		return ret;



	preempt_disable();

	if (!kernel_text_address((unsigned long) p->addr) ||

	    in_kprobes_functions((unsigned long) p->addr)) {
@@ -757,26 +795,6 @@ int __kprobes register_kprobe(struct kprobe *p) 
}

EXPORT_SYMBOL_GPL(register_kprobe);



/* Check passed kprobe is valid and return kprobe in kprobe_table. */

static struct kprobe * __kprobes __get_valid_kprobe(struct kprobe *p)

{

	struct kprobe *old_p, *list_p;



	old_p = get_kprobe(p->addr);

	if (unlikely(!old_p))

		return NULL;



	if (p != old_p) {

		list_for_each_entry_rcu(list_p, &old_p->list, list)

			if (list_p == p)

			/* kprobe p is a valid probe */

				goto valid;

		return NULL;

	}

valid:

	return old_p;

}



/*

 * Unregister a kprobe without a scheduler synchronization.

 */