On 09/01, Ales Novak wrote: > > On ptrace_detach(), the TIF_SYSCALL_TRACE in thread->flags of the tracee > is not cleared up. This results in the tracehook_report_syscall_* being > called (though there's no longer a tracer listening to that) upon its > further syscalls. > > Example scenario - attach "strace" to a running process and kill it (the > strace) with SIGKILL. You'll see that the syscall trace hooks are still > being called.
We do not really care, if the tracer dies the tracee can be in the inconsistent state anyway. > --- a/kernel/ptrace.c > +++ b/kernel/ptrace.c > @@ -85,6 +85,7 @@ void __ptrace_unlink(struct task_struct *child) > task_clear_jobctl_pending(child, JOBCTL_TRAP_MASK); > task_clear_jobctl_trapping(child); > > + clear_tsk_thread_flag(child, TIF_SYSCALL_TRACE); OK, probably this change makes sense anyway, but then you should remove another clear_tsk_thread_flag(TIF_SYSCALL_TRACE) in ptrace_detach? And I'd suggest to move this clear_tsk_thread_flag() up, before spin_lock(siglock). Otherwise it looks as if we should clear this flag with ->siglock held. Oleg.
