In legacy mode, virtio_pci_queue_enabled() falls back to
virtio_queue_enabled() to know if the queue is enabled.
But virtio_queue_enabled() calls again virtio_pci_queue_enabled()
if k->queue_enabled is set. This ends in a crash after a stack
overflow.
The problem can be reproduced with
"-device virtio-net-pci,disable-legacy=off,disable-modern=true
-net tap,vhost=on"
And a look to the backtrace is very explicit:
...
#4 0x000000010029a438 in virtio_queue_enabled ()
#5 0x0000000100497a9c in virtio_pci_queue_enabled ()
...
#130902 0x000000010029a460 in virtio_queue_enabled ()
#130903 0x0000000100497a9c in virtio_pci_queue_enabled ()
#130904 0x000000010029a460 in virtio_queue_enabled ()
#130905 0x0000000100454a20 in vhost_net_start ()
...
This patch fixes the problem by introducing a new function
for the legacy case and calls it from virtio_pci_queue_enabled().
It also calls it from virtio_queue_enabled() to avoid code duplication.
Fixes: f19bcdfedd ("virtio-pci: implement queue_enabled method")
Cc: Jason Wang <jasowang@redhat.com>
Cc: Cindy Lu <lulu@redhat.com>
CC: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Laurent Vivier <lvivier@redhat.com>
Message-Id: <20200727153319.43716-1-lvivier@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
0c9753ebda