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From:   Michael Zaidman <michael.zaidman@gmail.com>
To:     jikos@kernel.org
Cc:     linux-kernel@vger.kernel.org, linux-input@vger.kernel.org,
        linux-i2c@vger.kernel.org, germain.hebert@ca.abb.com,
        Enrik.Berkhan@inka.de, Michael Zaidman <michael.zaidman@gmail.com>
Subject: [PATCH v3 11/12] HID: ft260: fix a NULL pointer dereference in ft260_i2c_write
Date:   Sun, 30 Oct 2022 22:34:02 +0200
Message-Id: <20221030203403.4637-12-michael.zaidman@gmail.com>
In-Reply-To: <20221030203403.4637-1-michael.zaidman@gmail.com>
References: <20221030203403.4637-1-michael.zaidman@gmail.com>
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The len=0 passed into the ft260_i2c_write() triggered the NULL
pointer dereference in the debug message on access to data[0].
Since a Write without data makes little sense in this context,
do not allow it.

Before:

$ sudo i2ctransfer -y 13 w0@0x51
Killed

After:

$ sudo i2ctransfer -y 13 w0@0x51
Error: Sending messages failed: Invalid argument

Reported-by: Enrik Berkhan <Enrik.Berkhan@inka.de>
Signed-off-by: Michael Zaidman <michael.zaidman@gmail.com>
---
 drivers/hid/hid-ft260.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/hid/hid-ft260.c b/drivers/hid/hid-ft260.c
index 00cbe7693ba0..b3f715f6ea86 100644
--- a/drivers/hid/hid-ft260.c
+++ b/drivers/hid/hid-ft260.c
@@ -395,6 +395,8 @@ static int ft260_i2c_write(struct ft260_device *dev, u8 addr, u8 *data,
 	struct ft260_i2c_write_request_report *rep =
 		(struct ft260_i2c_write_request_report *)dev->write_buf;
 
+	if (len < 1)
+		return -EINVAL;
 
 	if (time_is_before_jiffies(dev->need_wakeup_at)) {
 		(void)ft260_xfer_status(dev);
-- 
2.34.1