linux-kernel - [PATCH AUTOSEL 6.6 25/40] HID: mcp2221: Allow IO to start during probe

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20231128210615.875085-25-sashal@kernel.org>
Date:   Tue, 28 Nov 2023 16:05:31 -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 25/40] HID: mcp2221: Allow IO to start during probe

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

[ Upstream commit 73ce9f1f2741a38f5d27393e627702ae2c46e6f2 ]

During the probe we add an I2C adapter and as soon as we add that adapter
it may be used for a transfer (e.g via the code in i2cdetect()).
Those transfers are not able to complete and time out. This is because the
HID raw_event callback (mcp2221_raw_event) will not be invoked until the
HID device's 'driver_input_lock' is marked up at the completion of the
probe in hid_device_probe(). This starves the driver of the responses it
is waiting for.
In order to allow the I2C transfers to complete while we are still in the
probe, start the IO once we have completed init of the HID device.

This issue seems to have been seen before and a patch was submitted but
it seems it was never accepted. See:
https://lore.kernel.org/all/20221103222714.21566-3-Enrik.Berkhan@inka.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, 2 insertions(+)

diff --git a/drivers/hid/hid-mcp2221.c b/drivers/hid/hid-mcp2221.c
index b95f31cf0fa21..aef0785c91cc2 100644
--- a/drivers/hid/hid-mcp2221.c
+++ b/drivers/hid/hid-mcp2221.c
@@ -1142,6 +1142,8 @@ static int mcp2221_probe(struct hid_device *hdev,
 	if (ret)
 		return ret;

+	hid_device_io_start(hdev);
+
 	/* Set I2C bus clock diviser */
 	if (i2c_clk_freq > 400)
 		i2c_clk_freq = 400;
-- 
2.42.0