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fix: add waitpid safety net after signalfd setup to prevent SIGCHLD race #40229

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Merged
benhillis merged 1 commit into from
Apr 20, 2026
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fix: add waitpid safety net after signalfd setup to prevent SIGCHLD race #40229

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10 changes: 10 additions & 0 deletions src/linux/init/init.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -2426,6 +2426,16 @@ Return Value:
FATAL_ERROR("signalfd failed {}", errno);
}

// Handle the case where the child already exited before signalfd was set up.
int Status{};
auto WaitResult = waitpid(distroInitPid.value(), &Status, WNOHANG);
if (WaitResult > 0 || (WaitResult < 0 && errno == ECHILD))
{
LOG_ERROR("Init has exited. Terminating distribution");
InitTerminateInstanceInternal(Config);
return;
}

PollDescriptors.resize(2);
PollDescriptors[1].fd = SignalFd.get();
PollDescriptors[1].events = POLLIN;
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