From 43cc5a0afe4184a7fafe1eba32b5a11bb69c9ce0 Mon Sep 17 00:00:00 2001
From: Yang Yingliang <yangyingliang@huawei.com>
Date: Tue, 12 Jul 2022 21:55:04 +0800
Subject: [PATCH] spi: Fix simplification of devm_spi_register_controller
Git-commit: 43cc5a0afe4184a7fafe1eba32b5a11bb69c9ce0
Patch-mainline: v6.0-rc1
References: git-fixes

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>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 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 562d6441c7fd..1c14d682ffed 100644
--- a/drivers/spi/spi.c
+++ b/drivers/spi/spi.c
@@ -3132,9 +3132,9 @@ 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);
 }
 
 /**
@@ -3153,13 +3153,22 @@ 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);
 
-- 
2.35.3