Re: [RESEND] HID: steam: Prevent NULL pointer dereference in steam_{recv,send}_report

Lee Jones
2022-09-12T11:48:00Z

On Wed, 03 Aug 2022, Lee Jones wrote:

> 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.

This patch has been floating around since the beginning of July.

It fixes a real issue which was found by creating a virtual
(software based) malicious device and registering it as a HID device.

There is nothing preventing a real attacker from creating a H/W
version of the device in order to instigate an out-of-bounds read,
potentially leading to a data leak.

Would someone be kind enough to review please?

> 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@kernel.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;
>

--
Lee Jones [李琼斯]