In the Linux kernel, the following vulnerability has been resolved: bluetooth/l2cap: sync sock recv cb and release The problem occurs between the system call to close the sock and hcirxwork, where the former releases the sock and the latter accesses it without lock protection. CPU0 CPU1 ---- ---- sockclose hcirxwork l2capsockrelease hciacldatapacket l2capsockkill l2caprecvframe skfree l2capconlesschannel l2capsockrecvcb If hcirx_work processes the data that needs to be received before the sock is closed, then everything is normal; Otherwise, the work thread may access the released sock when receiving data. Add a chan mutex in the rx callback of the sock to achieve synchronization between the sock release and recv cb. Sock is dead, so set chan data to NULL, avoid others use invalid sock pointer.