Messages in this thread | | | Date | Fri, 2 Sep 2016 14:25:39 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH] ptrace: clear TIF_SYSCALL_TRACE on ptrace detach |
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On 09/01, Ales Novak wrote: > > On __ptrace_detach(), called from do_exit()->exit_notify()-> > forget_original_parent()->exit_ptrace(), 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.
To clarify, this patch can't really fix the problem(s), The tracee can be killed by SIGTRAP in this case. Again, we do not care too much, a lot of bad things can happen if the tracer dies.
But I agree, this patch makes the things better for free,
Acked-by: Oleg Nesterov <oleg@redhat.com>
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