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bug:fix fd doesn't close in time #4404

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bug:fix fd doesn't close in time #4404

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1 change: 1 addition & 0 deletions libcontainer/standard_init_linux.go
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Original file line number Diff line number Diff line change
Expand Up @@ -260,6 +260,7 @@ func (l *linuxStandardInit) Init() error {
return &os.PathError{Op: "write exec fifo", Path: fifoPath, Err: err}
}

_ = unix.Close(fd)
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I don't think it's a bug. If you look at the code, you'll see that the parent process uses handleFifoResult to read all data from the fifo and (once it's closed from the other side) remove it.

Now, the presence of exec.fifo file is used to distinguish between the created and the running state, as you can see in (*container).RefreshState function.

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Obviously, we don't have any tests to check if the container state is reported correctly for the case when the startContainer hook is still running (which is what this PR essentially breaks).

If you have some time, feel free to write such a test @ningmingxiao

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Is it necessary to call "unix.Close(fd)" before to run startcontainer hook?

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Is it necessary to call "unix.Close(fd)" before to run startcontainer hook?

No, it's not necessary. As I explained above, it only affects that the container status will be. Once it's closed, the runc status will show "running". This is why, I think, this commit is a mistake.

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thank you.

// Close the O_PATH fifofd fd before exec because the kernel resets
// dumpable in the wrong order. This has been fixed in newer kernels, but
// we keep this to ensure CVE-2016-9962 doesn't re-emerge on older kernels.
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