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From:   Sasha Levin <sashal@kernel.org>
To:     linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc:     Oliver Neukum <oneukum@suse.com>,
        syzbot+965152643a75a56737be@syzkaller.appspotmail.com,
        Jiri Kosina <jkosina@suse.cz>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: [PATCH 5.2 024/135] HID: holtek: test for sanity of intfdata
Date:   Thu, 22 Aug 2019 13:06:20 -0400
Message-Id: <20190822170811.13303-25-sashal@kernel.org>
In-Reply-To: <20190822170811.13303-1-sashal@kernel.org>
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From: Oliver Neukum <oneukum@suse.com>

commit 01ec0a5f19c8c82960a07f6c7410fc9e01d7fb51 upstream.

The ioctl handler uses the intfdata of a second interface,
which may not be present in a broken or malicious device, hence
the intfdata needs to be checked for NULL.

[jkosina@suse.cz: fix newly added spurious space]
Reported-by: syzbot+965152643a75a56737be@syzkaller.appspotmail.com
Signed-off-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 drivers/hid/hid-holtek-kbd.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/hid/hid-holtek-kbd.c b/drivers/hid/hid-holtek-kbd.c
index b3d502421b79d..0a38e8e9bc783 100644
--- a/drivers/hid/hid-holtek-kbd.c
+++ b/drivers/hid/hid-holtek-kbd.c
@@ -123,9 +123,14 @@ static int holtek_kbd_input_event(struct input_dev *dev, unsigned int type,
 
 	/* Locate the boot interface, to receive the LED change events */
 	struct usb_interface *boot_interface = usb_ifnum_to_if(usb_dev, 0);
+	struct hid_device *boot_hid;
+	struct hid_input *boot_hid_input;
 
-	struct hid_device *boot_hid = usb_get_intfdata(boot_interface);
-	struct hid_input *boot_hid_input = list_first_entry(&boot_hid->inputs,
+	if (unlikely(boot_interface == NULL))
+		return -ENODEV;
+
+	boot_hid = usb_get_intfdata(boot_interface);
+	boot_hid_input = list_first_entry(&boot_hid->inputs,
 		struct hid_input, list);
 
 	return boot_hid_input->input->event(boot_hid_input->input, type, code,
-- 
2.20.1