InputFile::setFrameBuffer seems to fail because the code is trying to dereference an iterator over it's bounds. 

This only happens if a previous setFrameBuffer call contained more channels than the current call.

-- in setFrameBuffer line 421 --
const FrameBuffer &oldFrameBuffer = _data->tFileBuffer;

FrameBuffer::ConstIterator i = oldFrameBuffer.begin();
FrameBuffer::ConstIterator j = frameBuffer.begin();

while (i != oldFrameBuffer.end())
{
    if (strcmp (i.name(), j.name()) || i.slice().type != j.slice().type) // if frameBuffer size < oldFrameBuffer size then j maybe invalid
break;
    ++i;
    ++j;
}
-- end code --

This code is in OpenEXR 1.4 and 1.6

A patch is attached.