Author: Lee, Chun-Yi <joeyli.kernel@gmail.com> Fengguang Wu run coccinelle and warns about: drivers/platform/x86/acer-wmi.c:1200:17-21: ERROR: obj is NULL but dereferenced. drivers/platform/x86/acer-wmi.c:891:17-21: ERROR: obj is NULL but dereferenced. drivers/platform/x86/acer-wmi.c:1953:17-21: ERROR: obj is NULL but dereferenced. It causes by the code in patch 987dfbaa65b2c3568b85e29d2598da08a011ee09 doesn’t check obj variable should not be NULL. There have risk for dereference a NULL …