In the Linux kernel, the following vulnerability has been resolved: net: dsa: mv88e6xxx: Correct check for empty list Since commit a3c53be55c95 ("net: dsa: mv88e6xxx: Support multiple MDIO busses") mv88e6xxxdefaultmdiobus() has checked that the return value of listfirstentry() is non-NULL. This appears to be intended to guard against the list chip->mdios being empty. However, it is not the correct check as the implementation of listfirstentry is not designed to return NULL for empty lists. Instead, use listfirstentryor_null() which does return NULL if the list is empty. Flagged by Smatch. Compile tested only.