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From:   Lee Jones <lee.jones@linaro.org>
To:     lee.jones@linaro.org
Cc:     linux-kernel@vger.kernel.org, Jiri Kosina <jikos@kernel.org>,
        Benjamin Tissoires <benjamin.tissoires@redhat.com>,
        linux-input@vger.kernel.org
Subject: [PATCH 1/1] HID: steam: Prevent NULL pointer dereference in steam_{recv,send}_report
Date:   Fri,  8 Jul 2022 08:40:09 +0100
Message-Id: <20220708074009.621113-1-lee.jones@linaro.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

It is possible for a malicious device to forgo submitting a Feature
Report.  The HID Steam driver presently makes no prevision for this
and de-references the 'struct hid_report' pointer obtained from the
HID devices without first checking its validity.  Let's change that.

Cc: Jiri Kosina <jikos@kernel.org>
Cc: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Cc: linux-input@vger.kernel.org
Fixes: c164d6abf3841 ("HID: add driver for Valve Steam Controller")
Signed-off-by: Lee Jones <lee.jones@linaro.org>
---
 drivers/hid/hid-steam.c | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/drivers/hid/hid-steam.c b/drivers/hid/hid-steam.c
index a3b151b29bd71..fc616db4231bb 100644
--- a/drivers/hid/hid-steam.c
+++ b/drivers/hid/hid-steam.c
@@ -134,6 +134,11 @@ static int steam_recv_report(struct steam_device *steam,
 	int ret;
 
 	r = steam->hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0];
+	if (!r) {
+		hid_err(steam->hdev, "No HID_FEATURE_REPORT submitted -  nothing to read\n");
+		return -EINVAL;
+	}
+
 	if (hid_report_len(r) < 64)
 		return -EINVAL;
 
@@ -165,6 +170,11 @@ static int steam_send_report(struct steam_device *steam,
 	int ret;
 
 	r = steam->hdev->report_enum[HID_FEATURE_REPORT].report_id_hash[0];
+	if (!r) {
+		hid_err(steam->hdev, "No HID_FEATURE_REPORT submitted -  nothing to read\n");
+		return -EINVAL;
+	}
+
 	if (hid_report_len(r) < 64)
 		return -EINVAL;
 
-- 
2.37.0.rc0.161.g10f37bed90-goog