CVE-2022-49977CVE-2022-49977

In the Linux kernel, the following vulnerability has been resolved: ftrace: Fix NULL pointer dereference in is_ftrace_trampoline when ftrace is dead ftrace_startup does not remove ops from ftrace_ops_list when ftrace_startup_enable fails: register_ftrace_function ftrace_startup __register_ftrace_function ... add_ftrace_ops(&ftrace_ops_list, ops) ... ... ftrace_startup_enable // if ftrace failed to modify, ftrace_disabled is set to 1 ... return 0 // ops is in the ftrace_ops_list. When ftrace_disabled = 1, unregister_ftrace_function simply returns without doing anything: unregister_ftrace_function ftrace_shutdown if (unlikely(ftrace_disabled)) return -ENODEV; // return here, __unregister_ftrace_function is not executed, // as a result, ops is still in the ftrace_ops_list __unregister_ftrace_function ... If ops is dynamically allocated, it will be free later, in this case, is_ftrace_trampoli