Messages in this thread | | | Date | Thu, 8 Nov 2018 10:16:38 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC PATCH] ptrace: add PTRACE_GET_SYSCALL_INFO request |
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On 11/07, Elvira Khabirova wrote: > > On Wed, 7 Nov 2018 17:44:44 +0100 > Oleg Nesterov <oleg@redhat.com> wrote: > > > To me PT_IN_SYSCALL_STOP makes no real sense, but I won't argue. > > > > At least I'd ask to not abuse task->ptrace. ptrace_report_syscall() can clear > > ->ptrace_message on exit if we really want PTRACE_GET_SYSCALL_INFO to fail after > > that. > > I really would not like to rely on ->ptrace_message remaining empty; > this looks too fragile.
Well. I do not understand why this is fragile. And certainly this is not more fragile than
current->ptrace |= PT_IN_SYSCALL_STOP; trace_notify(); current->ptrace &= ~PT_IN_SYSCALL_STOP;
simply because both ->ptrace updates are technically wrong. The tracee can race with the exiting tracer which clears ->ptrace.
But even if this was correct. This patch manipulates ->ptrace_message anyway, I do not understand why should we abuse ->ptrace too just to for the sanity check in PTRACE_GET_SYSCALL_INFO.
Oleg.
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