In the Linux kernel, the following vulnerability has been resolved: netfilter: conntrack: Avoid nfcthelperhash uses after free If nfconntrackinitstart() fails (for example due to a registernfconntrackbpf() failure), the nfconntrackhelperfini() clean-up path frees the nfcthelperhash map. When built with NFCONNTRACK=y, further netfilter modules (e.g: netfilterconntrackftp) can still be loaded and call nfconntrackhelpersregister(), independently of whether nfconntrack initialized correctly. This accesses the nfcthelperhash dangling pointer and causes a uaf, possibly leading to random memory corruption. This patch guards nfconntrackhelperregister() from accessing a freed or uninitialized nfcthelper_hash pointer and fixes possible uses-after-free when loading a conntrack module.