From d9d4b1e46d9543a82c23f6df03f4ad697dab361b Mon Sep 17 00:00:00 2001 From: Alan Stern Date: Thu, 3 Oct 2019 14:53:59 -0400 Subject: HID: Fix assumption that devices have inputs The syzbot fuzzer found a slab-out-of-bounds write bug in the hid-gaff driver. The problem is caused by the driver's assumption that the device must have an input report. While this will be true for all normal HID input devices, a suitably malicious device can violate the assumption. The same assumption is present in over a dozen other HID drivers. This patch fixes them by checking that the list of hid_inputs for the hid_device is nonempty before allowing it to be used. Reported-and-tested-by: syzbot+403741a091bf41d4ae79@syzkaller.appspotmail.com Signed-off-by: Alan Stern CC: Signed-off-by: Benjamin Tissoires --- drivers/hid/hid-lg4ff.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'drivers/hid/hid-lg4ff.c') diff --git a/drivers/hid/hid-lg4ff.c b/drivers/hid/hid-lg4ff.c index 03f0220062ca..5e6a0cef2a06 100644 --- a/drivers/hid/hid-lg4ff.c +++ b/drivers/hid/hid-lg4ff.c @@ -1253,8 +1253,8 @@ static int lg4ff_handle_multimode_wheel(struct hid_device *hid, u16 *real_produc int lg4ff_init(struct hid_device *hid) { - struct hid_input *hidinput = list_entry(hid->inputs.next, struct hid_input, list); - struct input_dev *dev = hidinput->input; + struct hid_input *hidinput; + struct input_dev *dev; struct list_head *report_list = &hid->report_enum[HID_OUTPUT_REPORT].report_list; struct hid_report *report = list_entry(report_list->next, struct hid_report, list); const struct usb_device_descriptor *udesc = &(hid_to_usb_dev(hid)->descriptor); @@ -1266,6 +1266,13 @@ int lg4ff_init(struct hid_device *hid) int mmode_ret, mmode_idx = -1; u16 real_product_id; + if (list_empty(&hid->inputs)) { + hid_err(hid, "no inputs found\n"); + return -ENODEV; + } + hidinput = list_entry(hid->inputs.next, struct hid_input, list); + dev = hidinput->input; + /* Check that the report looks ok */ if (!hid_validate_values(hid, HID_OUTPUT_REPORT, 0, 0, 7)) return -1; -- cgit v1.2.3