In the Linux kernel, the following vulnerability has been resolved: net/handshake: fix null-ptr-deref in handshake_nl_done_doit() We should not call trace_handshake_cmd_done_err() if socket lookup has failed. Also we should call trace_handshake_cmd_done_err() before releasing the file, otherwise dereferencing sock->sk can return garbage. This also reverts 7afc6d0a107f ("net/handshake: Fix uninitialized local variable") Unable to handle kernel paging request at virtual address dfff800000000003 KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f] Mem abort info: ESR = 0x0000000096000005 EC = 0x25: DABT (current EL), IL = 32 bits SET = 0, FnV = 0 EA = 0, S1PTW = 0 FSC = 0x05: level 1 translation fault Data abort info: ISV = 0, ISS = 0x00000005, ISS2 = 0x00000000 CM = 0,