linux-kernel - [PATCH -next] platform/chrome: Fix off-by-one error in wilco

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Date:   Wed, 20 Feb 2019 14:58:27 -0700
From:   Nick Crews <ncrews@...omium.org>
To:     bleung@...omium.org, enric.balletbo@...labora.com
Cc:     linux-kernel@...r.kernel.org, kernel-janitors@...r.kernel.org,
        dan.carpenter@...cle.com, dlaurie@...omium.org, ncrews@...omium.org
Subject: [PATCH -next] platform/chrome: Fix off-by-one error in wilco_ec/debugfs.c

Before, in debugfs.c it was possible to supply only the message type,
and not supply any other arguments when sending raw commands. However,
this is never used by the EC, and it led to an underflow error. Now,
just don't allow too short of a command, we will never need
that anyways.

Fixes: 46c7fd06f8c9 ("platform/chrome: wilco_ec: Add support for raw commands in debugfs")
Signed-off-by: Nick Crews <ncrews@...omium.org>
---
 drivers/platform/chrome/wilco_ec/debugfs.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/platform/chrome/wilco_ec/debugfs.c b/drivers/platform/chrome/wilco_ec/debugfs.c
index 46ff3b6c46c7..c090db2cd5be 100644
--- a/drivers/platform/chrome/wilco_ec/debugfs.c
+++ b/drivers/platform/chrome/wilco_ec/debugfs.c
@@ -136,8 +136,8 @@ static ssize_t raw_write(struct file *file, const char __user *user_buf,
 	ret = parse_hex_sentence(buf, kcount, request_data, TYPE_AND_DATA_SIZE);
 	if (ret < 0)
 		return ret;
-	/* Need at least two bytes for message type */
-	if (ret < 2)
+	/* Need at least two bytes for message type and one for command */
+	if (ret < 3)
 		return -EINVAL;
 
 	/* Clear response data buffer */
@@ -145,7 +145,7 @@ static ssize_t raw_write(struct file *file, const char __user *user_buf,
 
 	msg.type = request_data[0] << 8 | request_data[1];
 	msg.flags = WILCO_EC_FLAG_RAW;
-	msg.command = ret > 2 ? request_data[2] : 0;
+	msg.command = request_data[2];
 	msg.request_data = ret > 3 ? request_data + 3 : 0;
 	msg.request_size = ret - 3;
 	msg.response_data = debug_info->raw_data;