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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, John Garry <john.garry@huawei.com>,
        Wei Xu <xuwei5@hisilicon.com>
Subject: [PATCH 5.2 115/143] bus: hisi_lpc: Unregister logical PIO range to avoid potential use-after-free
Date:   Wed,  4 Sep 2019 19:54:18 +0200
Message-Id: <20190904175318.893845918@linuxfoundation.org>
In-Reply-To: <20190904175314.206239922@linuxfoundation.org>
References: <20190904175314.206239922@linuxfoundation.org>
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From: John Garry <john.garry@huawei.com>

commit 1b15a5632a809ab57d403fd972ca68785363b654 upstream.

If, after registering a logical PIO range, the driver probe later fails,
the logical PIO range memory will be released automatically.

This causes an issue, in that the logical PIO range is not unregistered
and the released range memory may be later referenced.

Fix by unregistering the logical PIO range.

And since we now unregister the logical PIO range for probe failure, avoid
the special ordering of setting logical PIO range ops, which was the
previous (poor) attempt at a safeguard against this.

Cc: stable@vger.kernel.org
Fixes: adf38bb0b595 ("HISI LPC: Support the LPC host on Hip06/Hip07 with DT bindings")
Signed-off-by: John Garry <john.garry@huawei.com>
Signed-off-by: Wei Xu <xuwei5@hisilicon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/bus/hisi_lpc.c |   11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

--- a/drivers/bus/hisi_lpc.c
+++ b/drivers/bus/hisi_lpc.c
@@ -606,24 +606,25 @@ static int hisi_lpc_probe(struct platfor
 	range->fwnode = dev->fwnode;
 	range->flags = LOGIC_PIO_INDIRECT;
 	range->size = PIO_INDIRECT_SIZE;
+	range->hostdata = lpcdev;
+	range->ops = &hisi_lpc_ops;
+	lpcdev->io_host = range;
 
 	ret = logic_pio_register_range(range);
 	if (ret) {
 		dev_err(dev, "register IO range failed (%d)!\n", ret);
 		return ret;
 	}
-	lpcdev->io_host = range;
 
 	/* register the LPC host PIO resources */
 	if (acpi_device)
 		ret = hisi_lpc_acpi_probe(dev);
 	else
 		ret = of_platform_populate(dev->of_node, NULL, NULL, dev);
-	if (ret)
+	if (ret) {
+		logic_pio_unregister_range(range);
 		return ret;
-
-	lpcdev->io_host->hostdata = lpcdev;
-	lpcdev->io_host->ops = &hisi_lpc_ops;
+	}
 
 	io_end = lpcdev->io_host->io_start + lpcdev->io_host->size;
 	dev_info(dev, "registered range [%pa - %pa]\n",