[PATCH 5.14 163/172] HID: betop: fix slab-out-of-bounds Write in betop_probe

Greg Kroah-Hartman
2021-10-04T13:40:55Z

From: F.A.Sulaiman <asha.16@itfac.mrt.ac.lk>

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>
---
drivers/hid/hid-betopff.c | 13 ++++++++++---
1 file changed, 10 insertions(+), 3 deletions(-)

--- a/drivers/hid/hid-betopff.c
+++ b/drivers/hid/hid-betopff.c
@@ -56,15 +56,22 @@ static int betopff_init(struct hid_devic
{
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;