[PATCH 1/8] kprobes: Fix error return and slot leak in __register_kprobe()

["Masami Hiramatsu (Google)" <mhiramat@kernel.org>]

From: Masami Hiramatsu (Google) <mhiramat@kernel.org>

When arm_kprobe() fails in __register_kprobe(), the probe is removed
from kprobe_table and synchronize_rcu() is executed, but the error code
ret was ignored and try_to_optimize_kprobe(p) was executed, returning 0.
Additionally, the instruction slot allocated by prepare_kprobe() was
leaked.

Fix this by releasing the instruction slot via arch_remove_kprobe(p)
and returning ret when arm_kprobe() fails.

Fixes: 587e8e6d640b ("kprobes: Adopt guard() and scoped_guard()")
Cc: stable@vger.kernel.org
Signed-off-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
---
 kernel/kprobes.c |    2 ++
 1 file changed, 2 insertions(+)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index 2441b9e39343..10946658bb35 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1946,6 +1946,8 @@ static int __register_kprobe(struct kprobe *p)
 		if (ret) {
 			hlist_del_rcu(&p->hlist);
 			synchronize_rcu();
+			arch_remove_kprobe(p);
+			return ret;
 		}
 	}