Messages in this thread | | | Subject | Re: [PATCH v2] Implement close-on-fork | From | Ralph Corderoy <> | Date | Sat, 18 Jun 2022 12:41:11 +0100 |
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Hi Nate,
> One manifestation of this is a race conditions in system(), which > (depending on the implementation) is non-atomic in that it first calls > a fork() and then an exec().
The need for O_CLOFORK might be made more clear by looking at a long-standing Go issue, i.e. unrelated to system(3), which was started in 2017 by Russ Cox when he summed up the current race-condition behaviour of trying to execve(2) a newly created file: https://github.com/golang/go/issues/22315. I raised it on linux-kernel in 2017, https://marc.info/?l=linux-kernel&m=150834137201488, and linked to a proposed patch from 2011, ‘[PATCH] fs: add FD_CLOFORK and O_CLOFORK’ by Changli Gao. As I said, long-standing.
The Go issue is worth a read. Russ wondered ‘What would Java do’ only to find that Java already had an issue open for the same problem since 2014.
I think the kernel is the place to fix the problem, just as with FD_CLOEXEC/O_CLOEXEC. Ian Lance Taylor says on the Go issue that it looks like ‘Solaris and macOS and OpenBSD have O_CLOFORK already. Hopefully it will catch on further’.
-- Cheers, Ralph.
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