linux-kernel - [PATCH v2 4/4] HID: i2c-hid: fix i2c_hid_get_raw

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: <1354716176-12558-5-git-send-email-benjamin.tissoires@gmail.com>
Date:	Wed,  5 Dec 2012 15:02:56 +0100
From:	Benjamin Tissoires <benjamin.tissoires@...il.com>
To:	Benjamin Tissoires <benjamin.tissoires@...il.com>,
	Jiri Kosina <jkosina@...e.cz>,
	Jean Delvare <khali@...ux-fr.org>, linux-input@...r.kernel.org,
	linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH v2 4/4] HID: i2c-hid: fix i2c_hid_get_raw_report count mismatches

The previous memcpy implementation relied on the size advertized by the
device. There were no guarantees that buf was big enough.

Some gymnastic is also required with the +2/-2 to take into account
the first 2 bytes of the returned buffer where the total returned
length is supplied by the device.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@...il.com>
---
 drivers/hid/i2c-hid/i2c-hid.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/hid/i2c-hid/i2c-hid.c b/drivers/hid/i2c-hid/i2c-hid.c
index c6630d4..ce01d59 100644
--- a/drivers/hid/i2c-hid/i2c-hid.c
+++ b/drivers/hid/i2c-hid/i2c-hid.c
@@ -502,23 +502,31 @@ static int i2c_hid_get_raw_report(struct hid_device *hid,
 {
 	struct i2c_client *client = hid->driver_data;
 	struct i2c_hid *ihid = i2c_get_clientdata(client);
+	size_t ret_count, ask_count;
 	int ret;
 
 	if (report_type == HID_OUTPUT_REPORT)
 		return -EINVAL;
 
-	if (count > ihid->bufsize)
-		count = ihid->bufsize;
+	/* +2 bytes to include the size of the reply in the query buffer */
+	ask_count = min(count + 2, (size_t)ihid->bufsize);
 
 	ret = i2c_hid_get_report(client,
 			report_type == HID_FEATURE_REPORT ? 0x03 : 0x01,
-			report_number, ihid->inbuf, count);
+			report_number, ihid->inbuf, ask_count);
 
 	if (ret < 0)
 		return ret;
 
-	count = ihid->inbuf[0] | (ihid->inbuf[1] << 8);
+	ret_count = ihid->inbuf[0] | (ihid->inbuf[1] << 8);
 
+	if (!ret_count)
+		return 0;
+
+	ret_count = min(ret_count, ask_count);
+
+	/* The query buffer contains the size, dropping it in the reply */
+	count = min(count, ret_count - 2);
 	memcpy(buf, ihid->inbuf + 2, count);
 
 	return count;
-- 
1.8.0.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/