| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.15 164/168] vhost: validate log when IOTLB is enabled | Date | Wed, 11 Apr 2018 00:25:06 +0200 |
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4.15-stable review patch. If anyone has any objections, please let me know.
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From: Jason Wang <jasowang@redhat.com>
[ Upstream commit d65026c6c62e7d9616c8ceb5a53b68bcdc050525 ]
Vq log_base is the userspace address of bitmap which has nothing to do with IOTLB. So it needs to be validated unconditionally otherwise we may try use 0 as log_base which may lead to pin pages that will lead unexpected result (e.g trigger BUG_ON() in set_bit_to_user()).
Fixes: 6b1e6cc7855b0 ("vhost: new device IOTLB API") Reported-by: syzbot+6304bf97ef436580fede@syzkaller.appspotmail.com Signed-off-by: Jason Wang <jasowang@redhat.com> Acked-by: Michael S. Tsirkin <mst@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> --- drivers/vhost/vhost.c | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-)
--- a/drivers/vhost/vhost.c +++ b/drivers/vhost/vhost.c @@ -1256,14 +1256,12 @@ static int vq_log_access_ok(struct vhost /* Caller should have vq mutex and device mutex */ int vhost_vq_access_ok(struct vhost_virtqueue *vq) { - if (vq->iotlb) { - /* When device IOTLB was used, the access validation - * will be validated during prefetching. - */ - return 1; - } - return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used) && - vq_log_access_ok(vq, vq->log_base); + int ret = vq_log_access_ok(vq, vq->log_base); + + if (ret || vq->iotlb) + return ret; + + return vq_access_ok(vq, vq->num, vq->desc, vq->avail, vq->used); } EXPORT_SYMBOL_GPL(vhost_vq_access_ok);
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