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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        "Naveen N. Rao" <naveen.n.rao@linux.vnet.ibm.com>,
        Ananth N Mavinakayanahalli <ananth@linux.ibm.com>,
        Masami Hiramatsu <mhiramat@kernel.org>,
        Wang ShaoBo <bobo.shaobowang@huawei.com>,
        Cheng Jian <cj.chengjian@huawei.com>,
        "Steven Rostedt (VMware)" <rostedt@goodmis.org>
Subject: [PATCH 4.9 29/43] kretprobe: Avoid re-registration of the same kretprobe earlier
Date:   Mon,  8 Feb 2021 16:00:55 +0100
Message-Id: <20210208145807.486860064@linuxfoundation.org>
In-Reply-To: <20210208145806.281758651@linuxfoundation.org>
References: <20210208145806.281758651@linuxfoundation.org>
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From: Wang ShaoBo <bobo.shaobowang@huawei.com>

commit 0188b87899ffc4a1d36a0badbe77d56c92fd91dc upstream.

Our system encountered a re-init error when re-registering same kretprobe,
where the kretprobe_instance in rp->free_instances is illegally accessed
after re-init.

Implementation to avoid re-registration has been introduced for kprobe
before, but lags for register_kretprobe(). We must check if kprobe has
been re-registered before re-initializing kretprobe, otherwise it will
destroy the data struct of kretprobe registered, which can lead to memory
leak, system crash, also some unexpected behaviors.

We use check_kprobe_rereg() to check if kprobe has been re-registered
before running register_kretprobe()'s body, for giving a warning message
and terminate registration process.

Link: https://lkml.kernel.org/r/20210128124427.2031088-1-bobo.shaobowang@huawei.com

Cc: stable@vger.kernel.org
Fixes: 1f0ab40976460 ("kprobes: Prevent re-registration of the same kprobe")
[ The above commit should have been done for kretprobes too ]
Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com>
Acked-by: Ananth N Mavinakayanahalli <ananth@linux.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@kernel.org>
Signed-off-by: Wang ShaoBo <bobo.shaobowang@huawei.com>
Signed-off-by: Cheng Jian <cj.chengjian@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/kprobes.c |    4 ++++
 1 file changed, 4 insertions(+)

--- a/kernel/kprobes.c
+++ b/kernel/kprobes.c
@@ -1884,6 +1884,10 @@ int register_kretprobe(struct kretprobe
 	int i;
 	void *addr;
 
+	/* If only rp->kp.addr is specified, check reregistering kprobes */
+	if (rp->kp.addr && check_kprobe_rereg(&rp->kp))
+		return -EINVAL;
+
 	if (kretprobe_blacklist_size) {
 		addr = kprobe_addr(&rp->kp);
 		if (IS_ERR(addr))