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