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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, Yang Yingliang <yangyingliang@huawei.com>,
        Conor Dooley <conor.dooley@microchip.com>,
        Mark Brown <broonie@kernel.org>,
        Sasha Levin <sashal@kernel.org>
Subject: [PATCH 5.18 0269/1095] spi: Fix simplification of devm_spi_register_controller
Date:   Mon, 15 Aug 2022 19:54:28 +0200
Message-Id: <20220815180440.876024149@linuxfoundation.org>
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From: Yang Yingliang <yangyingliang@huawei.com>

[ Upstream commit 43cc5a0afe4184a7fafe1eba32b5a11bb69c9ce0 ]

This reverts commit 59ebbe40fb51 ("spi: simplify
devm_spi_register_controller").

If devm_add_action() fails in devm_add_action_or_reset(),
devm_spi_unregister() will be called, it decreases the
refcount of 'ctlr->dev' to 0, then it will cause uaf in
the drivers that calling spi_put_controller() in error path.

Fixes: 59ebbe40fb51 ("spi: simplify devm_spi_register_controller")
Signed-off-by: Yang Yingliang <yangyingliang@huawei.com>
Reviewed-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20220712135504.1055688-1-yangyingliang@huawei.com
Signed-off-by: Mark Brown <broonie@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/spi/spi.c | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/drivers/spi/spi.c b/drivers/spi/spi.c
index e1065768c537..6a8850e62078 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -3068,9 +3068,9 @@ int spi_register_controller(struct spi_controller *ctlr)
 }
 EXPORT_SYMBOL_GPL(spi_register_controller);
 
-static void devm_spi_unregister(void *ctlr)
+static void devm_spi_unregister(struct device *dev, void *res)
 {
-	spi_unregister_controller(ctlr);
+	spi_unregister_controller(*(struct spi_controller **)res);
 }
 
 /**
@@ -3089,13 +3089,22 @@ static void devm_spi_unregister(void *ctlr)
 int devm_spi_register_controller(struct device *dev,
 				 struct spi_controller *ctlr)
 {
+	struct spi_controller **ptr;
 	int ret;
 
+	ptr = devres_alloc(devm_spi_unregister, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return -ENOMEM;
+
 	ret = spi_register_controller(ctlr);
-	if (ret)
-		return ret;
+	if (!ret) {
+		*ptr = ctlr;
+		devres_add(dev, ptr);
+	} else {
+		devres_free(ptr);
+	}
 
-	return devm_add_action_or_reset(dev, devm_spi_unregister, ctlr);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(devm_spi_register_controller);
 
-- 
2.35.1