HID: betop: fix slab-out-of-bounds Write in betop_probe

commit 1e4ce418b1cb1a810256b5fb3fd33d22d1325993 upstream.

Syzbot reported slab-out-of-bounds Write bug in hid-betopff driver.
The problem is the driver assumes the device must have an input report but
some malicious devices violate this assumption.

So this patch checks hid_device's input is non empty before it's been used.

Reported-by: syzbot+07efed3bc5a1407bd742@syzkaller.appspotmail.com
Signed-off-by: F.A. SULAIMAN <asha.16@itfac.mrt.ac.lk>
Reviewed-by: Pavel Skripkin <paskripkin@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hid/hid-betopff.c b/drivers/hid/hid-betopff.c
index 69cfc8dc6af1e3459951898b9dc2cfe098cf4e6d..9b60efe6ec441e45a6b21f93047dcb88bf0cdf41 100644 (file)
--- a/drivers/hid/hid-betopff.c
+++ b/drivers/hid/hid-betopff.c
@@ -59,15 +59,22 @@ static int betopff_init(struct hid_device *hid)
 {
        struct betopff_device *betopff;
        struct hid_report *report;
-       struct hid_input *hidinput =
-                       list_first_entry(&hid->inputs, struct hid_input, list);
+       struct hid_input *hidinput;
        struct list_head *report_list =
                        &hid->report_enum[HID_OUTPUT_REPORT].report_list;
-       struct input_dev *dev = hidinput->input;
+       struct input_dev *dev;
        int field_count = 0;
        int error;
        int i, j;
 
+       if (list_empty(&hid->inputs)) {
+               hid_err(hid, "no inputs found\n");
+               return -ENODEV;
+       }
+
+       hidinput = list_first_entry(&hid->inputs, struct hid_input, list);
+       dev = hidinput->input;
+
        if (list_empty(report_list)) {
                hid_err(hid, "no output reports found\n");
                return -ENODEV;