From e5b50fe7bea43d0658773c89ba410ecc56867ee6 Mon Sep 17 00:00:00 2001 From: Benjamin Tissoires Date: Wed, 5 Dec 2012 15:02:56 +0100 Subject: 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 Signed-off-by: Jiri Kosina --- drivers/hid/i2c-hid/i2c-hid.c | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) (limited to 'drivers/hid/i2c-hid') 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; -- cgit v1.1