linux-kernel - [PATCH] riscv/kprobe: reclaim insn

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Message-ID: <20220523015124.98743-1-liaochang1@huawei.com>
Date:   Mon, 23 May 2022 09:51:24 +0800
From:   Liao Chang <liaochang1@...wei.com>
To:     <paul.walmsley@...ive.com>, <palmer@...belt.com>,
        <aou@...s.berkeley.edu>, <mhiramat@...nel.org>,
        <rostedt@...dmis.org>, <peterz@...radead.org>,
        <jszhang@...nel.org>, <liaochang1@...wei.com>,
        <naveen.n.rao@...ux.vnet.ibm.com>
CC:     <linux-riscv@...ts.infradead.org>, <linux-kernel@...r.kernel.org>
Subject: [PATCH] riscv/kprobe: reclaim insn_slot on kprobe unregistration

On kprobe registration kernel allocate one insn_slot for new kprobe,
but it forget to reclaim the insn_slot on unregistration, leading to a
potential leakage.

This bug reported by Chen Guokai <chenguokai17@...ls.ucas.ac.cn>.

Signed-off-by: Liao Chang <liaochang1@...wei.com>
---
 arch/riscv/kernel/probes/kprobes.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/riscv/kernel/probes/kprobes.c b/arch/riscv/kernel/probes/kprobes.c
index e6e950b7cf32..f12eb1fbb52c 100644
--- a/arch/riscv/kernel/probes/kprobes.c
+++ b/arch/riscv/kernel/probes/kprobes.c
@@ -110,6 +110,10 @@ void __kprobes arch_disarm_kprobe(struct kprobe *p)
 
 void __kprobes arch_remove_kprobe(struct kprobe *p)
 {
+	if (p->ainsn.api.insn) {
+		free_insn_slot(p->ainsn.api.insn, 0);
+		p->ainsn.api.insn = NULL;
+	}
 }
 
 static void __kprobes save_previous_kprobe(struct kprobe_ctlblk *kcb)
-- 
2.17.1