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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, Aaron Ma <aaron.ma@canonical.com>,
        Jiri Kosina <jkosina@suse.cz>
Subject: [PATCH 3.18 18/52] HID: i2c-hid: fix size check and type usage
Date:   Sun, 22 Apr 2018 15:53:51 +0200
Message-Id: <20180422135316.112014588@linuxfoundation.org>
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3.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Aaron Ma <aaron.ma@canonical.com>

commit ac75a041048b8c1f7418e27621ca5efda8571043 upstream.

When convert char array with signed int, if the inbuf[x] is negative then
upper bits will be set to 1. Fix this by using u8 instead of char.

ret_size has to be at least 3, hid_input_report use it after minus 2 bytes.

Cc: stable@vger.kernel.org
Signed-off-by: Aaron Ma <aaron.ma@canonical.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/hid/i2c-hid/i2c-hid.c |   13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -136,10 +136,10 @@ struct i2c_hid {
 						   * register of the HID
 						   * descriptor. */
 	unsigned int		bufsize;	/* i2c buffer size */
-	char			*inbuf;		/* Input buffer */
-	char			*rawbuf;	/* Raw Input buffer */
-	char			*cmdbuf;	/* Command buffer */
-	char			*argsbuf;	/* Command arguments buffer */
+	u8			*inbuf;		/* Input buffer */
+	u8			*rawbuf;	/* Raw Input buffer */
+	u8			*cmdbuf;	/* Command buffer */
+	u8			*argsbuf;	/* Command arguments buffer */
 
 	unsigned long		flags;		/* device flags */
 
@@ -373,7 +373,8 @@ static int i2c_hid_hwreset(struct i2c_cl
 
 static void i2c_hid_get_input(struct i2c_hid *ihid)
 {
-	int ret, ret_size;
+	int ret;
+	u32 ret_size;
 	int size = le16_to_cpu(ihid->hdesc.wMaxInputLength);
 
 	if (size > ihid->bufsize)
@@ -398,7 +399,7 @@ static void i2c_hid_get_input(struct i2c
 		return;
 	}
 
-	if (ret_size > size) {
+	if ((ret_size > size) || (ret_size <= 2)) {
 		dev_err(&ihid->client->dev, "%s: incomplete report (%d/%d)\n",
 			__func__, size, ret_size);
 		return;