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-lgff.c | 11 +++++++++-- 1 file changed, 9 insertions(+), 2 deletions(-) (limited to 'drivers/hid/hid-lgff.c') diff --git a/drivers/hid/hid-lgff.c b/drivers/hid/hid-lgff.c index c79a6ec43745..aed4ddc397a9 100644 --- a/drivers/hid/hid-lgff.c +++ b/drivers/hid/hid-lgff.c @@ -115,12 +115,19 @@ static void hid_lgff_set_autocenter(struct input_dev *dev, u16 magnitude) int lgff_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; const signed short *ff_bits = ff_joystick; int error; int i; + 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 -ENODEV; -- cgit v1.2.3