HID: picolcd: Prevent NULL pointer dereference on _remove()

When picolcd is switched into bootloader mode (for FW flashing) make sure not to try to dereference NULL-pointers of feature-devices during unplug/unbind. This fixes following BUG: BUG: unable to handle kernel NULL pointer dereference at 0298 IP: [] picolcd_exit_framebuffer+0x1b/0x80 [hid_

Re: [PATCH 13/14] HID: picolcd_core: validate output report details

Hi Kees, Jiri, On Wed, 28 August 2013 Jiri Kosina wrote: > From: Kees Cook > > A HID device could send a malicious output report that would cause the > picolcd HID driver to trigger a NULL dereference during attr file writing. > > CVE-2013-2899 > > Signed-off-by: Kees Cook > Cc: sta...@kerne