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由 Jason Gerecke 提交于
The wacom_get_hdev_data function is used to find and return a reference to the "other half" of a Wacom device (i.e., the touch device associated with a pen, or vice-versa). To ensure these references are properly accounted for, the function is supposed to automatically increment the refcount before returning. This was not done, however, for devices which have pen & touch on different interfaces of the same USB device. This can lead to a WARNING ("refcount_t: underflow; use-after-free") when removing the module or device as we call kref_put() more times than kref_get(). Triggering an "actual" use- after-free would be difficult since both devices will disappear nearly- simultaneously. To silence this warning and prevent the potential error, we need to increment the refcount for all cases within wacom_get_hdev_data. Fixes: 41372d5d ("HID: wacom: Augment 'oVid' and 'oPid' with heuristics for HID_GENERIC") Cc: <stable@vger.kernel.org> # v4.9+ Signed-off-by: NJason Gerecke <jason.gerecke@wacom.com> Reviewed-by: NPing Cheng <ping.cheng@wacom.com> Signed-off-by: NJiri Kosina <jkosina@suse.cz>
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