linux-kernel - [PATCH] spi: tegra20-slink: fix UAF in tegra_slink

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Date:   Wed, 13 Jul 2022 17:40:23 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     <linux-kernel@...r.kernel.org>, <linux-spi@...r.kernel.org>,
        <linux-tegra@...r.kernel.org>
CC:     <broonie@...nel.org>, <digetx@...il.com>
Subject: [PATCH] spi: tegra20-slink: fix UAF in tegra_slink_remove()

After calling spi_unregister_master(), the refcount of master will
be decrease to 0, and it will be freed in spi_controller_release(),
the device data also will be freed, so it will lead a UAF when using
'tspi'. To fix this, get the master before unregister and put it when
finish using it.

Fixes: 26c863418221 ("spi: tegra20-slink: Don't use resource-managed spi_register helper")
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
---
 drivers/spi/spi-tegra20-slink.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/spi/spi-tegra20-slink.c b/drivers/spi/spi-tegra20-slink.c
index 38360434d6e9..148043d0c2b8 100644
--- a/drivers/spi/spi-tegra20-slink.c
+++ b/drivers/spi/spi-tegra20-slink.c
@@ -1136,7 +1136,7 @@ static int tegra_slink_probe(struct platform_device *pdev)
 
 static int tegra_slink_remove(struct platform_device *pdev)
 {
-	struct spi_master *master = platform_get_drvdata(pdev);
+	struct spi_master *master = spi_master_get(platform_get_drvdata(pdev));
 	struct tegra_slink_data	*tspi = spi_master_get_devdata(master);
 
 	spi_unregister_master(master);
@@ -1151,6 +1151,7 @@ static int tegra_slink_remove(struct platform_device *pdev)
 	if (tspi->rx_dma_chan)
 		tegra_slink_deinit_dma_param(tspi, true);
 
+	spi_master_put(master);
 	return 0;
 }
 
-- 
2.25.1