linux-kernel - [PATCH] kprobes: Rollback kprobe flags on failed arm

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Message-Id: <20220602073259.25669-1-nashuiliang@gmail.com>
Date:   Thu,  2 Jun 2022 15:32:59 +0800
From:   Chuang <nashuiliang@...il.com>
To:     unlisted-recipients:; (no To-header on input)
Cc:     Chuang Wang <nashuiliang@...il.com>,
        Jingren Zhou <zhoujingren@...iglobal.com>,
        "Naveen N. Rao" <naveen.n.rao@...ux.ibm.com>,
        Anil S Keshavamurthy <anil.s.keshavamurthy@...el.com>,
        "David S. Miller" <davem@...emloft.net>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] kprobes: Rollback kprobe flags on failed arm_kprobe

From: Chuang Wang <nashuiliang@...il.com>

In aggrprobe scenes, if arm_kprobe() returns an error(e.g. livepatch and
kprobe are using the same function X), kprobe flags, while has been
modified to ~KPROBE_FLAG_DISABLED, is not rollled back.

Then, __disable_kprobe() will be failed in __unregister_kprobe_top(),
the kprobe list will be not removed from aggrprobe, memory leaks or
illegal pointers will be caused.

WARN disarm_kprobe:
 Failed to disarm kprobe-ftrace at 00000000c729fdbc (-2)
 RIP: 0010:disarm_kprobe+0xcc/0x110
 Call Trace:
  __disable_kprobe+0x78/0x90
  __unregister_kprobe_top+0x13/0x1b0
  ? _cond_resched+0x15/0x30
  unregister_kprobes+0x32/0x80
  unregister_kprobe+0x1a/0x20

Illegal Pointers:
 BUG: unable to handle kernel paging request at 0000000000656369
 RIP: 0010:__get_valid_kprobe+0x69/0x90
 Call Trace:
  register_kprobe+0x30/0x60
  __register_trace_kprobe.part.7+0x8b/0xc0
  create_local_trace_kprobe+0xd2/0x130
  perf_kprobe_init+0x83/0xd0

Signed-off-by: Chuang Wang <nashuiliang@...il.com>
Signed-off-by: Jingren Zhou <zhoujingren@...iglobal.com>
---
 kernel/kprobes.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/kernel/kprobes.c b/kernel/kprobes.c
index f214f8c088ed..96c75e23113c 100644
--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -2422,8 +2422,10 @@ int enable_kprobe(struct kprobe *kp)
 	if (!kprobes_all_disarmed && kprobe_disabled(p)) {
 		p->flags &= ~KPROBE_FLAG_DISABLED;
 		ret = arm_kprobe(p);
-		if (ret)
+		if (ret) {
 			p->flags |= KPROBE_FLAG_DISABLED;
+			kp->flags |= KPROBE_FLAG_DISABLED;
+		}
 	}
 out:
 	mutex_unlock(&kprobe_mutex);
-- 
2.34.1