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kprobes: Prevent re-registration of the same kprobe

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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: Ananth N Mavinakayanahalli<[email protected]>
Acked-by: Masami Hiramatsu <[email protected]>
Cc: Jim Keniston <[email protected]>
Cc: Andi Kleen <[email protected]>
Cc: Christoph Hellwig <[email protected]>
Cc: Frank Ch. Eigler <[email protected]>
Cc: Frederic Weisbecker <[email protected]>
Cc: H. Peter Anvin <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Jason Baron <[email protected]>
Cc: K.Prasad <[email protected]>
Cc: Lai Jiangshan <[email protected]>
Cc: Li Zefan <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Srikar Dronamraju <[email protected]>
Cc: Steven Rostedt <[email protected]>
Cc: Tom Zanussi <[email protected]>
LKML-Reference: <[email protected]>
Signed-off-by: Frederic Weisbecker <[email protected]>
This commit is contained in:
Ananth N Mavinakayanahalli 2009-09-15 10:43:07 +05:30 • committed by Frederic Weisbecker
commit 1f0ab40976
1 changed files with 38 additions and 20 deletions
Download patch file Download diff file Expand all files Collapse all files

58
kernel/kprobes.c
View file

@ -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 @@ out:
}
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.
*/