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commit 1b93f4032a246e0aa43c2f424921e0aace57b994
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Author: Eugene Syromyatnikov <evgsyr@gmail.com>
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Date: Fri Aug 4 11:33:04 2017 +0200
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Improve handling of unexpected tracees
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When receiving a ptrace stop of an unexpected child, handle it
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in the most transparent way possible:
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- detach it instead of PTRACE_CONT'ing;
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- send it the signal with which it has been stopped.
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This should hopefully help to deal with processes that have been created
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with misused CLONE_PTRACE flag set.
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* strace.c (maybe_allocate_tcb) <WIFSTOPPED(status) && !followfork>:
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Calculate the signal similarly to the way next_event does,
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forward it to the unexpected tracee, and detach the tracee.
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commit 7a35b711df127664e7430b2644ae92c75f3d5f67
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Author: Dmitry V. Levin <ldv@altlinux.org>
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Date: Sun Aug 6 13:27:07 2017 +0000
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Fix handling of unexpected tracees when PTRACE_SEIZE is not in use
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* strace.c (maybe_allocate_tcb) <WIFSTOPPED(status) && !followfork>:
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The expected ptrace stop signal in case of !use seize is not
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syscall_trap_sig but SIGSTOP. An idea of using PTRACE_GETSIGINFO to
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distinguish signal stops that should be re-injected from other kinds
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of stops didn't work out due to kernel implementation peculiarities
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of initial ptrace-stop.
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commit 330f4633d5103938982602b6f21f761570e3482c
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Author: Dmitry V. Levin <ldv@altlinux.org>
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Date: Sun Aug 6 15:10:56 2017 +0000
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Simplify handling of unexpected tracees
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* strace.c (maybe_allocate_tcb) <WIFSTOPPED(status) && !followfork>:
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Remove the dance around possible re-injection of WSTOPSIG(status)
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as the only observable stop here is the initial ptrace-stop.
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diff -rup a/strace.c b/strace.c
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--- a/strace.c 2017-08-31 14:04:21.000000000 -0400
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+++ b/strace.c 2017-08-31 14:51:32.523134570 -0400
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@@ -1958,11 +1958,15 @@ maybe_allocate_tcb(const int pid, int st
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error_msg("Process %d attached", pid);
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return tcp;
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} else {
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- /* This can happen if a clone call used
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- * CLONE_PTRACE itself.
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+ /*
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+ * This can happen if a clone call misused CLONE_PTRACE itself.
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+ *
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+ * There used to be a dance around possible re-injection of
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+ * WSTOPSIG(status), but it was later removed as the only
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+ * observable stop here is the initial ptrace-stop.
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*/
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- ptrace(PTRACE_CONT, pid, (char *) 0, 0);
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- error_msg("Stop of unknown pid %u seen, PTRACE_CONTed it", pid);
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+ ptrace(PTRACE_DETACH, pid, NULL, 0L);
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+ error_msg("Detached unknown pid %d", pid);
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return NULL;
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}
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}
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