Commit b0399092 authored Sep 18, 2020 by Muchun Song Committed by Linus Torvalds Sep 19, 2020

kprobes: fix kill kprobe which has been marked as gone



If a kprobe is marked as gone, we should not kill it again.  Otherwise, we
can disarm the kprobe more than once.  In that case, the statistics of
kprobe_ftrace_enabled can unbalance which can lead to that kprobe do not
work.

Fixes: e8386a0c ("kprobes: support probing module __exit function")
Co-developed-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Cc: "Naveen N . Rao" <naveen.n.rao@linux.ibm.com>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Song Liu <songliubraving@fb.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: <stable@vger.kernel.org>
Link: https://lkml.kernel.org/r/20200822030055.32383-1-songmuchun@bytedance.com


Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent bb3e96d6

kernel/kprobes.c

+8 −1

Original line number	Diff line number	Diff line
		@@ -2140,6 +2140,9 @@ static void kill_kprobe(struct kprobe *p)

		lockdep_assert_held(&kprobe_mutex);

		if (WARN_ON_ONCE(kprobe_gone(p)))
		return;

		p->flags \|= KPROBE_FLAG_GONE;
		if (kprobe_aggrprobe(p)) {
		/*
		@@ -2419,7 +2422,10 @@ static int kprobes_module_callback(struct notifier_block *nb,
		mutex_lock(&kprobe_mutex);
		for (i = 0; i < KPROBE_TABLE_SIZE; i++) {
		head = &kprobe_table[i];
		hlist_for_each_entry(p, head, hlist)
		hlist_for_each_entry(p, head, hlist) {
		if (kprobe_gone(p))
		continue;

		if (within_module_init((unsigned long)p->addr, mod) \|\|
		(checkcore &&
		within_module_core((unsigned long)p->addr, mod))) {
		@@ -2437,6 +2443,7 @@ static int kprobes_module_callback(struct notifier_block *nb,
		kill_kprobe(p);
		}
		}
		}
		if (val == MODULE_STATE_GOING)
		remove_module_kprobe_blacklist(mod);
		mutex_unlock(&kprobe_mutex);

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