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From:   Yu-Che Cheng <giver@chromium.org>
To:     James Lo <james.lo@mediatek.com>, Stephen Boyd <sboyd@kernel.org>,
        Matthias Brugger <matthias.bgg@gmail.com>
Cc:     Yu-Che Cheng <giver@chromium.org>, Fei Shao <fshao@chromium.org>,
        AngeloGioacchino Del Regno 
        <angelogioacchino.delregno@collabora.com>,
        linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org,
        linux-mediatek@lists.infradead.org
Subject: [PATCH] spmi: mediatek: Fix UAF on device remove
Date:   Mon, 17 Jul 2023 17:39:35 +0800
Message-ID: <20230717173934.1.If004a6e055a189c7f2d0724fa814422c26789839@changeid>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

The pmif driver data that contains the clocks is allocated along with
spmi_controller.
On device remove, spmi_controller will be freed first, and then devres
, including the clocks, will be cleanup.
This leads to UAF because putting the clocks will access the clocks in
the pmif driver data, which is already freed along with spmi_controller.

This can be reproduced by enabling DEBUG_TEST_DRIVER_REMOVE and
building the kernel with KASAN.

Fix the UAF issue by using unmanaged clk_bulk_get() and putting the
clocks before freeing spmi_controller.

Reported-by: Fei Shao <fshao@chromium.org>
Signed-off-by: Yu-Che Cheng <giver@chromium.org>
---

 drivers/spmi/spmi-mtk-pmif.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/spmi/spmi-mtk-pmif.c b/drivers/spmi/spmi-mtk-pmif.c
index b3c991e1ea40..74b73f9bc222 100644
--- a/drivers/spmi/spmi-mtk-pmif.c
+++ b/drivers/spmi/spmi-mtk-pmif.c
@@ -465,7 +465,7 @@ static int mtk_spmi_probe(struct platform_device *pdev)
 	for (i = 0; i < arb->nclks; i++)
 		arb->clks[i].id = pmif_clock_names[i];
 
-	err = devm_clk_bulk_get(&pdev->dev, arb->nclks, arb->clks);
+	err = clk_bulk_get(&pdev->dev, arb->nclks, arb->clks);
 	if (err) {
 		dev_err(&pdev->dev, "Failed to get clocks: %d\n", err);
 		goto err_put_ctrl;
@@ -474,7 +474,7 @@ static int mtk_spmi_probe(struct platform_device *pdev)
 	err = clk_bulk_prepare_enable(arb->nclks, arb->clks);
 	if (err) {
 		dev_err(&pdev->dev, "Failed to enable clocks: %d\n", err);
-		goto err_put_ctrl;
+		goto err_put_clks;
 	}
 
 	ctrl->cmd = pmif_arb_cmd;
@@ -498,6 +498,8 @@ static int mtk_spmi_probe(struct platform_device *pdev)
 
 err_domain_remove:
 	clk_bulk_disable_unprepare(arb->nclks, arb->clks);
+err_put_clks:
+	clk_bulk_put(arb->nclks, arb->clks);
 err_put_ctrl:
 	spmi_controller_put(ctrl);
 	return err;
@@ -509,6 +511,7 @@ static void mtk_spmi_remove(struct platform_device *pdev)
 	struct pmif *arb = spmi_controller_get_drvdata(ctrl);
 
 	clk_bulk_disable_unprepare(arb->nclks, arb->clks);
+	clk_bulk_put(arb->nclks, arb->clks);
 	spmi_controller_remove(ctrl);
 	spmi_controller_put(ctrl);
 }
-- 
2.41.0.255.g8b1d071c50-goog