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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,
        Simon Gaiser <simon@invisiblethingslab.com>,
        Juergen Gross <jgross@suse.com>,
        Boris Ostrovsky <boris.ostrovsky@oracle.com>,
        Sasha Levin <alexander.levin@microsoft.com>
Subject: [PATCH 4.16 037/279] xen: xenbus_dev_frontend: Really return response string
Date:   Mon, 18 Jun 2018 10:10:22 +0200
Message-Id: <20180618080610.343312695@linuxfoundation.org>
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4.16-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Simon Gaiser <simon@invisiblethingslab.com>

[ Upstream commit ebf04f331fa15a966262341a7dc6b1a0efd633e4 ]

xenbus_command_reply() did not actually copy the response string and
leaked stack content instead.

Fixes: 9a6161fe73bd ("xen: return xenstore command failures via response instead of rc")
Signed-off-by: Simon Gaiser <simon@invisiblethingslab.com>
Reviewed-by: Juergen Gross <jgross@suse.com>
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/xen/xenbus/xenbus_dev_frontend.c |    3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

--- a/drivers/xen/xenbus/xenbus_dev_frontend.c
+++ b/drivers/xen/xenbus/xenbus_dev_frontend.c
@@ -403,7 +403,7 @@ static int xenbus_command_reply(struct x
 {
 	struct {
 		struct xsd_sockmsg hdr;
-		const char body[16];
+		char body[16];
 	} msg;
 	int rc;
 
@@ -412,6 +412,7 @@ static int xenbus_command_reply(struct x
 	msg.hdr.len = strlen(reply) + 1;
 	if (msg.hdr.len > sizeof(msg.body))
 		return -E2BIG;
+	memcpy(&msg.body, reply, msg.hdr.len);
 
 	mutex_lock(&u->reply_mutex);
 	rc = queue_reply(&u->read_buffers, &msg, sizeof(msg.hdr) + msg.hdr.len);