linux-kernel - [PATCH AUTOSEL 6.6 24/40] HID: mcp2221: Set driver data before I2C adapter add

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Message-ID: <20231128210615.875085-24-sashal@kernel.org>
Date:   Tue, 28 Nov 2023 16:05:30 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Hamish Martin <hamish.martin@...iedtelesis.co.nz>,
        Jiri Kosina <jkosina@...e.cz>, Sasha Levin <sashal@...nel.org>,
        gupt21@...il.com, jikos@...nel.org, benjamin.tissoires@...hat.com,
        linux-i2c@...r.kernel.org, linux-input@...r.kernel.org
Subject: [PATCH AUTOSEL 6.6 24/40] HID: mcp2221: Set driver data before I2C adapter add

From: Hamish Martin <hamish.martin@...iedtelesis.co.nz>

[ Upstream commit f2d4a5834638bbc967371b9168c0b481519f7c5e ]

The process of adding an I2C adapter can invoke I2C accesses on that new
adapter (see i2c_detect()).

Ensure we have set the adapter's driver data to avoid null pointer
dereferences in the xfer functions during the adapter add.

This has been noted in the past and the same fix proposed but not
completed. See:
https://lore.kernel.org/lkml/ef597e73-ed71-168e-52af-0d19b03734ac@vigem.de/

Signed-off-by: Hamish Martin <hamish.martin@...iedtelesis.co.nz>
Signed-off-by: Jiri Kosina <jkosina@...e.cz>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/hid/hid-mcp2221.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/hid/hid-mcp2221.c b/drivers/hid/hid-mcp2221.c
index 72883e0ce7575..b95f31cf0fa21 100644
--- a/drivers/hid/hid-mcp2221.c
+++ b/drivers/hid/hid-mcp2221.c
@@ -1157,12 +1157,12 @@ static int mcp2221_probe(struct hid_device *hdev,
 	snprintf(mcp->adapter.name, sizeof(mcp->adapter.name),
 			"MCP2221 usb-i2c bridge");
 
+	i2c_set_adapdata(&mcp->adapter, mcp);
 	ret = devm_i2c_add_adapter(&hdev->dev, &mcp->adapter);
 	if (ret) {
 		hid_err(hdev, "can't add usb-i2c adapter: %d\n", ret);
 		return ret;
 	}
-	i2c_set_adapdata(&mcp->adapter, mcp);
 
 #if IS_REACHABLE(CONFIG_GPIOLIB)
 	/* Setup GPIO chip */
-- 
2.42.0