From: Muchun Song songmuchun@bytedance.com Subject: 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.

Link: https://lkml.kernel.org/r/20200822030055.32383-1-songmuchun@bytedance.com Fixes: e8386a0cb22f ("kprobes: support probing module __exit function") Signed-off-by: Muchun Song songmuchun@bytedance.com Co-developed-by: Chengming Zhou zhouchengming@bytedance.com Signed-off-by: Chengming Zhou zhouchengming@bytedance.com 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 Signed-off-by: Andrew Morton akpm@linux-foundation.org ---

kernel/kprobes.c | 9 ++++++++- 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/kernel/kprobes.c~kprobes-fix-kill-kprobe-which-has-been-marked-as-gone +++ a/kernel/kprobes.c @@ -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(struc 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))) { @@ -2436,6 +2442,7 @@ static int kprobes_module_callback(struc */ kill_kprobe(p); } + } } if (val == MODULE_STATE_GOING) remove_module_kprobe_blacklist(mod); _