tree 458b84a40d30ed494712d9772c07c91240544c75
parent 7a546af50eb78ab99840903083231eb635c8a566
author Jason Gerecke <killertofu@gmail.com> 1484696338 -0800
committer Jiri Kosina <jkosina@suse.cz> 1484831965 +0100

HID: wacom: Fix sibling detection regression

Commit 345857b ("HID: wacom: generic: Add support for sensor offsets") included
a change to the operation and location of the call to 'wacom_add_shared_data'
in 'wacom_parse_and_register'. The modifications included moving it higher up
so that it would occur before the call to 'wacom_retrieve_hid_descriptor'. This
was done to prevent a crash that would have occured when the report containing
tablet offsets was fed into the driver with 'wacom_hid_report_raw_event'
(specifically: the various 'wacom_wac_*_report' functions were written with the
assumption that they would only be called once tablet setup had completed;
'wacom_wac_pen_report' in particular dereferences 'shared' which wasn't yet
allocated).

Moving the call to 'wacom_add_shared_data' effectively prevented the crash but
also broke the sibiling detection code which assumes that the HID descriptor
has been read and the various device_type flags set.

To fix this situation, we restore the original 'wacom_add_shared_data'
operation and location and instead implement an alternative change that can
also prevent the crash. Specifically, we notice that the report functions
mentioned above expect to be called only for input reports.  By adding a check,
we can prevent feature reports (such as the offset report) from
causing trouble.

Fixes: 345857bb49 ("HID: wacom: generic: Add support for sensor offsets")
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Tested-by: Ping Cheng <pingc@wacom.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>