Problems in Subprocesses of Tracees

Robert O'Callahan robert at ocallahan.org
Sat Dec 9 02:23:37 UTC 2017


Your explanation makes sense. I don't really have any idea what the bug
could be.

One way to narrow down the divergence would be to inject additional dummy
syscalls (could be anything, even just an invalid syscall number) into the
trace between the last known good point and the divergence. For example
between the print, close and exit. If you can inject them into if_print
that would help too. Basically, the control flow seems to diverge between
recording and replay and those divergences are only detected at traced
syscall boundaries, so inserting more of those boundaries narrows down the
window during which control flow diverges. The control flow probably
diverges based on some data value so if we narrow it down enough we can
figure out what the changed data value is.

Rob
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