From 01ae49199e6a67075b53150ecd8dfc627a67183b Mon Sep 17 00:00:00 2001 From: Cornelia Huck Date: Fri, 9 Nov 2012 14:54:12 +1030 Subject: [PATCH] virtio: Don't access index after unregister. MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit commit 237242bddc99041e15a4ca51b8439657cadaff17 upstream. Virtio wants to release used indices after the corresponding virtio device has been unregistered. However, virtio does not hold an extra reference, giving up its last reference with device_unregister(), making accessing dev->index afterwards invalid. I actually saw problems when testing my (not-yet-merged) virtio-ccw code: - device_add virtio-net,id=xxx -> creates device virtio with n>0 - device_del xxx -> deletes virtio, but calls ida_simple_remove with an index of 0 - device_add virtio-net,id=xxx -> tries to add virtio0, which is still in use... So let's save the index we want to release before calling device_unregister(). Signed-off-by: Cornelia Huck Acked-by: Sjur Brændeland Signed-off-by: Rusty Russell Signed-off-by: Greg Kroah-Hartman --- drivers/virtio/virtio.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c index c3b3f7f0d9d19..abd47c7452d2b 100644 --- a/drivers/virtio/virtio.c +++ b/drivers/virtio/virtio.c @@ -225,8 +225,10 @@ EXPORT_SYMBOL_GPL(register_virtio_device); void unregister_virtio_device(struct virtio_device *dev) { + int index = dev->index; /* save for after device release */ + device_unregister(&dev->dev); - ida_simple_remove(&virtio_index_ida, dev->index); + ida_simple_remove(&virtio_index_ida, index); } EXPORT_SYMBOL_GPL(unregister_virtio_device); -- 2.47.2