Michael S. Tsirkin
2021-Sep-05 16:17 UTC
[PATCH] vhost_net: Convert from atomic_t to refcount_t on vhost_net_ubuf_ref->refcount
On Sat, Jul 17, 2021 at 06:20:30PM +0800, Xiyu Yang wrote:> refcount_t type and corresponding API can protect refcounters from > accidental underflow and overflow and further use-after-free situations. > > Signed-off-by: Xiyu Yang <xiyuyang19 at fudan.edu.cn> > Signed-off-by: Xin Tan <tanxin.ctf at gmail.com>Pls resubmit after addressing the build bot comments. Thanks!> --- > drivers/vhost/net.c | 14 ++++++++------ > 1 file changed, 8 insertions(+), 6 deletions(-) > > diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c > index 6414bd5741b8..e23150ca7d4c 100644 > --- a/drivers/vhost/net.c > +++ b/drivers/vhost/net.c > @@ -5,6 +5,7 @@ > * virtio-net server in host kernel. > */ > > +#include <linux/refcount.h> > #include <linux/compat.h> > #include <linux/eventfd.h> > #include <linux/vhost.h> > @@ -92,7 +93,7 @@ struct vhost_net_ubuf_ref { > * 1: no outstanding ubufs > * >1: outstanding ubufs > */ > - atomic_t refcount; > + refcount_t refcount; > wait_queue_head_t wait; > struct vhost_virtqueue *vq; > }; > @@ -240,7 +241,7 @@ vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy) > ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL); > if (!ubufs) > return ERR_PTR(-ENOMEM); > - atomic_set(&ubufs->refcount, 1); > + refcount_set(&ubufs->refcount, 1); > init_waitqueue_head(&ubufs->wait); > ubufs->vq = vq; > return ubufs; > @@ -248,7 +249,8 @@ vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy) > > static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs) > { > - int r = atomic_sub_return(1, &ubufs->refcount); > + refcount_dec(&ubufs->refcount); > + int r = refcount_read(&ubufs->refcount); > if (unlikely(!r)) > wake_up(&ubufs->wait); > return r; > @@ -257,7 +259,7 @@ static int vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs) > static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs) > { > vhost_net_ubuf_put(ubufs); > - wait_event(ubufs->wait, !atomic_read(&ubufs->refcount)); > + wait_event(ubufs->wait, !refcount_read(&ubufs->refcount)); > } > > static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs) > @@ -909,7 +911,7 @@ static void handle_tx_zerocopy(struct vhost_net *net, struct socket *sock) > ctl.ptr = ubuf; > msg.msg_controllen = sizeof(ctl); > ubufs = nvq->ubufs; > - atomic_inc(&ubufs->refcount); > + refcount_inc(&ubufs->refcount); > nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV; > } else { > msg.msg_control = NULL; > @@ -1384,7 +1386,7 @@ static void vhost_net_flush(struct vhost_net *n) > vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs); > mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex); > n->tx_flush = false; > - atomic_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1); > + refcount_set(&n->vqs[VHOST_NET_VQ_TX].ubufs->refcount, 1); > mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex); > } > } > -- > 2.7.4