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x/sys/windows/registry: Remove arbitrary string limit from setStringValue #12493

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folbricht opened this issue Sep 4, 2015 · 3 comments
Closed

x/sys/windows/registry: Remove arbitrary string limit from setStringValue #12493

folbricht opened this issue Sep 4, 2015 · 3 comments
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FrozenDueToAge OS-Windows
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Unplanned

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@folbricht
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setStringValue in https://github.com/golang/sys/blob/master/windows/registry/value.go enforces a max string size of 1<<10 which is arbitrary (on some Windows versions there is no limit enforced, see https://msdn.microsoft.com/en-us/library/windows/desktop/ms724872(v=vs.85).aspx). If the string is longer than that, the current function triggers slice bounds out of range.

Current implementation:

func (k Key) setStringValue(name string, valtype uint32, value string) error {
    v, err := syscall.UTF16FromString(value)
    if err != nil {
        return err
    }
    buf := (*[1 << 10]byte)(unsafe.Pointer(&v[0]))[:len(v)*2]
    return k.setValue(name, valtype, buf)
}

I propose using a byte buffer to do the []uint16 to []byte conversion, removing the string limit.

func (k Key) setStringValue(name string, valtype uint32, value string) error {
    v, err := syscall.UTF16FromString(value)
    if err != nil {
        return err
    }
    buf := new(bytes.Buffer)
    buf.Grow(len(v)*2)
    binary.Write(buf, binary.LittleEndian, v)
    return k.setValue(name, valtype, buf.Bytes())
}
@ianlancetaylor
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Just change the 1 << 10 to 1 << 30. That number doesn't matter, as long as it is larger than len(v)*2.

@ianlancetaylor ianlancetaylor added this to the Unplanned milestone Sep 4, 2015
@alexbrainman
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Try this https://go-review.googlesource.com/14287

Alex

alexbrainman added a commit that referenced this issue Sep 4, 2015
@alexbrainman
internal/syscall/windows/registry: do not panic when data is large
13e06d8 
Allow registry blobs to be as large as 500MB

Update #12493

Change-Id: I1d0e5c10772d25f8e7e17fed6e2e7dd12ca4e7cf
Reviewed-on: https://go-review.googlesource.com/14287
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
@gopherbot
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CL https://golang.org/cl/14288 mentions this issue.

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@ianlancetaylor @folbricht @gopherbot @alexbrainman