On Mon, Jul 13, 2015 at 09:53:43AM +0200, Gerd Hoffmann wrote: > On Mo, 2015-07-13 at 10:36 +0300, Michael S. Tsirkin wrote: > > On Mon, Jul 13, 2015 at 01:46:47PM +0800, Jason Wang wrote: > > > We abort on unaligned read/write in > > > virtio_address_space_read()/write() but since len in under control of > > > guest so qemu will simply crash when booting a modern guest (guest is > > > try to read when len is zero). > > > read. > > > > How can len be 0? Isn't this a guest bug? Or is this > > a theoretical issue? > > Something dumping pci config space? > With pci access capability not being used before and therefore zeroed? > Then hitting the "data" field will trigger a zero-length read.
I suspect so, yes. All this worries me: what if length was not 0 because the capability was previously used e.g. by bios? > That assert actually triggers when booting a recent linux kernel with > disable-modern=off > > cheers, > Gerd > Which linux version? Doesn't seem to trigger for me ... -- MST
