| Message ID | 20220623062446.16944-1-johan@kernel.org |
|---|---|
| State | Accepted |
| Commit | 039d4ed3428cf9c2052048d177880ebd02104764 |
| Headers | show |
| Series | [v2] Input: usbtouchscreen - add driver_info sanity check | expand |
On Mon, Jun 27, 2022 at 09:46:27AM +0200, Johan Hovold wrote: > On Thu, Jun 23, 2022 at 08:59:52AM -0700, Dmitry Torokhov wrote: > > On Thu, Jun 23, 2022 at 08:24:46AM +0200, Johan Hovold wrote: > > > Add a sanity check on the device id-table driver_info field to make sure > > > we never access a type structure (and function pointers) outside of the > > > device info array (e.g. if someone fails to ifdef a device-id entry). > > > > > > Note that this also suppresses a compiler warning with -Warray-bounds > > > (gcc-11.3.0) when compile-testing the driver without enabling any of > > > the device type Kconfig options: > > > > > > drivers/input/touchscreen/usbtouchscreen.c: In function 'usbtouch_probe': > > > drivers/input/touchscreen/usbtouchscreen.c:1668:16:warning: array subscript <unknown> is outside array bounds of 'struct usbtouch_device_info[0]' [-Warray-bounds] > > > 1668 | type = &usbtouch_dev_info[id->driver_info]; > > > > > > Signed-off-by: Johan Hovold <johan@kernel.org> > > > --- > > > > > > Changes in v2 > > > - use ARRAY_SIZE() for the sanity check (Dmitry) > > > - drop the dummy entry and combine the two patches as the sanity check > > > itself is enough to suppress the compiler warning (Dmitry) > > > - use -ENODEV instead of -EINVAL even if this means no error will be > > > logged in the unlikely event of a future driver bug > > > > Is this on purpose or because I happened to have used this error code > > when I suggested the change? I'm fine with returning -EINVAL there. > > It was on purpose. Returning -EINVAL (invalid argument) here just > doesn't seem quite right. I skimmed the errno list for a better > alternative, but decided -ENODEV works as well. > > If there's ever a driver bug that triggers this, you could say the > device isn't supported in that configuration. ;) > > If you prefer -EINVAL, I'll change it back. No, that is fine, I was simply making sure. Applied, thank you.
diff --git a/drivers/input/touchscreen/usbtouchscreen.c b/drivers/input/touchscreen/usbtouchscreen.c index 43c521f50c85..b01d026588c8 100644 --- a/drivers/input/touchscreen/usbtouchscreen.c +++ b/drivers/input/touchscreen/usbtouchscreen.c @@ -1654,6 +1654,9 @@ static int usbtouch_probe(struct usb_interface *intf, if (id->driver_info == DEVTYPE_IGNORE) return -ENODEV; + if (id->driver_info >= ARRAY_SIZE(usbtouch_dev_info)) + return -ENODEV; + endpoint = usbtouch_get_input_endpoint(intf->cur_altsetting); if (!endpoint) return -ENXIO;
Add a sanity check on the device id-table driver_info field to make sure we never access a type structure (and function pointers) outside of the device info array (e.g. if someone fails to ifdef a device-id entry). Note that this also suppresses a compiler warning with -Warray-bounds (gcc-11.3.0) when compile-testing the driver without enabling any of the device type Kconfig options: drivers/input/touchscreen/usbtouchscreen.c: In function 'usbtouch_probe': drivers/input/touchscreen/usbtouchscreen.c:1668:16:warning: array subscript <unknown> is outside array bounds of 'struct usbtouch_device_info[0]' [-Warray-bounds] 1668 | type = &usbtouch_dev_info[id->driver_info]; Signed-off-by: Johan Hovold <johan@kernel.org> --- Changes in v2 - use ARRAY_SIZE() for the sanity check (Dmitry) - drop the dummy entry and combine the two patches as the sanity check itself is enough to suppress the compiler warning (Dmitry) - use -ENODEV instead of -EINVAL even if this means no error will be logged in the unlikely event of a future driver bug drivers/input/touchscreen/usbtouchscreen.c | 3 +++ 1 file changed, 3 insertions(+)