[PATCH 5.8 104/118] kprobes: fix kill kprobe which has been marked as gone

Greg Kroah-Hartman
2020-09-21T16:53:53Z

From: Muchun Song <songmuchun@bytedance.com>

commit b0399092ccebd9feef68d4ceb8d6219a8c0caa05 upstream.

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: e8386a0cb22f ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2108,6 +2108,9 @@ 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)) {
/*
@@ -2365,7 +2368,10 @@ 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))) {
@@ -2382,6 +2388,7 @@ static int kprobes_module_callback(struc
*/
kill_kprobe(p);
}
+ }
}
if (val == MODULE_STATE_GOING)
remove_module_kprobe_blacklist(mod);