Jason Wang
2022-Jun-29 08:36 UTC
[PATCH] virtio-net: fix the race between refill work and close
On Wed, Jun 29, 2022 at 3:29 PM Michael S. Tsirkin <mst at redhat.com> wrote:> > On Tue, Jun 28, 2022 at 05:03:24PM +0800, Jason Wang wrote: > > We try using cancel_delayed_work_sync() to prevent the work from > > enabling NAPI. This is insufficient since we don't disable the the > > source the scheduling > > can't parse this sentenceI actually meant "we don't disable the source of the refill work scheduling".> > > of the refill work. This means an NAPI > > what do you mean "an NAPI"? a NAPI poll callback?Yes.> > > after > > cancel_delayed_work_sync() can schedule the refill work then can > > re-enable the NAPI that leads to use-after-free [1]. > > > > Since the work can enable NAPI, we can't simply disable NAPI before > > calling cancel_delayed_work_sync(). So fix this by introducing a > > dedicated boolean to control whether or not the work could be > > scheduled from NAPI. > > > > [1] > > =================================================================> > BUG: KASAN: use-after-free in refill_work+0x43/0xd4 > > Read of size 2 at addr ffff88810562c92e by task kworker/2:1/42 > > > > CPU: 2 PID: 42 Comm: kworker/2:1 Not tainted 5.19.0-rc1+ #480 > > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 > > Workqueue: events refill_work > > Call Trace: > > <TASK> > > dump_stack_lvl+0x34/0x44 > > print_report.cold+0xbb/0x6ac > > ? _printk+0xad/0xde > > ? refill_work+0x43/0xd4 > > kasan_report+0xa8/0x130 > > ? refill_work+0x43/0xd4 > > refill_work+0x43/0xd4 > > process_one_work+0x43d/0x780 > > worker_thread+0x2a0/0x6f0 > > ? process_one_work+0x780/0x780 > > kthread+0x167/0x1a0 > > ? kthread_exit+0x50/0x50 > > ret_from_fork+0x22/0x30 > > </TASK> > > ... > > > > Fixes: b2baed69e605c ("virtio_net: set/cancel work on ndo_open/ndo_stop") > > Signed-off-by: Jason Wang <jasowang at redhat.com> > > --- > > drivers/net/virtio_net.c | 38 ++++++++++++++++++++++++++++++++++++-- > > 1 file changed, 36 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > index db05b5e930be..21bf1e5c81ef 100644 > > --- a/drivers/net/virtio_net.c > > +++ b/drivers/net/virtio_net.c > > @@ -251,6 +251,12 @@ struct virtnet_info { > > /* Does the affinity hint is set for virtqueues? */ > > bool affinity_hint_set; > > > > + /* Is refill work enabled? */ > > + bool refill_work_enabled; > > + > > + /* The lock to synchronize the access to refill_work_enabled */ > > + spinlock_t refill_lock; > > + > > /* CPU hotplug instances for online & dead */ > > struct hlist_node node; > > struct hlist_node node_dead; > > @@ -348,6 +354,20 @@ static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask) > > return p; > > } > > > > +static void enable_refill_work(struct virtnet_info *vi) > > +{ > > + spin_lock(&vi->refill_lock); > > + vi->refill_work_enabled = true; > > + spin_unlock(&vi->refill_lock); > > +} > > + > > +static void disable_refill_work(struct virtnet_info *vi) > > +{ > > + spin_lock(&vi->refill_lock); > > + vi->refill_work_enabled = false; > > + spin_unlock(&vi->refill_lock); > > +} > > + > > static void virtqueue_napi_schedule(struct napi_struct *napi, > > struct virtqueue *vq) > > { > > @@ -1527,8 +1547,12 @@ static int virtnet_receive(struct receive_queue *rq, int budget, > > } > > > > if (rq->vq->num_free > min((unsigned int)budget, virtqueue_get_vring_size(rq->vq)) / 2) { > > - if (!try_fill_recv(vi, rq, GFP_ATOMIC)) > > - schedule_delayed_work(&vi->refill, 0); > > + if (!try_fill_recv(vi, rq, GFP_ATOMIC)) { > > + spin_lock(&vi->refill_lock); > > + if (vi->refill_work_enabled) > > + schedule_delayed_work(&vi->refill, 0); > > + spin_unlock(&vi->refill_lock); > > + } > > } > > > > u64_stats_update_begin(&rq->stats.syncp); > > @@ -1651,6 +1675,8 @@ static int virtnet_open(struct net_device *dev) > > struct virtnet_info *vi = netdev_priv(dev); > > int i, err; > > > > + enable_refill_work(vi); > > + > > for (i = 0; i < vi->max_queue_pairs; i++) { > > if (i < vi->curr_queue_pairs) > > /* Make sure we have some buffers: if oom use wq. */ > > @@ -2033,6 +2059,8 @@ static int virtnet_close(struct net_device *dev) > > struct virtnet_info *vi = netdev_priv(dev); > > int i; > > > > + /* Make sure NAPI doesn't schedule refill work */ > > + disable_refill_work(vi); > > /* Make sure refill_work doesn't re-enable napi! */ > > cancel_delayed_work_sync(&vi->refill); > > > > @@ -2776,6 +2804,9 @@ static void virtnet_freeze_down(struct virtio_device *vdev) > > netif_tx_lock_bh(vi->dev); > > netif_device_detach(vi->dev); > > netif_tx_unlock_bh(vi->dev); > > + /* Make sure NAPI doesn't schedule refill work */ > > + disable_refill_work(vi); > > + /* Make sure refill_work doesn't re-enable napi! */ > > cancel_delayed_work_sync(&vi->refill); > > > > if (netif_running(vi->dev)) { > > @@ -2799,6 +2830,8 @@ static int virtnet_restore_up(struct virtio_device *vdev) > > > > virtio_device_ready(vdev); > > > > + enable_refill_work(vi); > > + > > if (netif_running(vi->dev)) { > > for (i = 0; i < vi->curr_queue_pairs; i++) > > if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL)) > > @@ -3548,6 +3581,7 @@ static int virtnet_probe(struct virtio_device *vdev) > > vdev->priv = vi; > > > > INIT_WORK(&vi->config_work, virtnet_config_changed_work); > > + spin_lock_init(&vi->refill_lock); > > > > /* If we can receive ANY GSO packets, we must allocate large ones. */ > > if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) || > > > Can't say I love all the extra state but oh well.I couldn't find a better way. The tricky part is that NAPI and refill can schedule each other so we need a third state. Thanks> > > -- > > 2.25.1 >
Michael S. Tsirkin
2022-Jun-29 08:44 UTC
[PATCH] virtio-net: fix the race between refill work and close
On Wed, Jun 29, 2022 at 04:36:12PM +0800, Jason Wang wrote:> On Wed, Jun 29, 2022 at 3:29 PM Michael S. Tsirkin <mst at redhat.com> wrote: > > > > On Tue, Jun 28, 2022 at 05:03:24PM +0800, Jason Wang wrote: > > > We try using cancel_delayed_work_sync() to prevent the work from > > > enabling NAPI. This is insufficient since we don't disable the the > > > source the scheduling > > > > can't parse this sentence > > I actually meant "we don't disable the source of the refill work scheduling". > > > > > > of the refill work. This means an NAPI > > > > what do you mean "an NAPI"? a NAPI poll callback? > > Yes.pls post with a fixed log then.> > > > > after > > > cancel_delayed_work_sync() can schedule the refill work then can > > > re-enable the NAPI that leads to use-after-free [1]. > > > > > > Since the work can enable NAPI, we can't simply disable NAPI before > > > calling cancel_delayed_work_sync(). So fix this by introducing a > > > dedicated boolean to control whether or not the work could be > > > scheduled from NAPI. > > > > > > [1] > > > =================================================================> > > BUG: KASAN: use-after-free in refill_work+0x43/0xd4 > > > Read of size 2 at addr ffff88810562c92e by task kworker/2:1/42 > > > > > > CPU: 2 PID: 42 Comm: kworker/2:1 Not tainted 5.19.0-rc1+ #480 > > > Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 > > > Workqueue: events refill_work > > > Call Trace: > > > <TASK> > > > dump_stack_lvl+0x34/0x44 > > > print_report.cold+0xbb/0x6ac > > > ? _printk+0xad/0xde > > > ? refill_work+0x43/0xd4 > > > kasan_report+0xa8/0x130 > > > ? refill_work+0x43/0xd4 > > > refill_work+0x43/0xd4 > > > process_one_work+0x43d/0x780 > > > worker_thread+0x2a0/0x6f0 > > > ? process_one_work+0x780/0x780 > > > kthread+0x167/0x1a0 > > > ? kthread_exit+0x50/0x50 > > > ret_from_fork+0x22/0x30 > > > </TASK> > > > ... > > > > > > Fixes: b2baed69e605c ("virtio_net: set/cancel work on ndo_open/ndo_stop") > > > Signed-off-by: Jason Wang <jasowang at redhat.com> > > > --- > > > drivers/net/virtio_net.c | 38 ++++++++++++++++++++++++++++++++++++-- > > > 1 file changed, 36 insertions(+), 2 deletions(-) > > > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > > index db05b5e930be..21bf1e5c81ef 100644 > > > --- a/drivers/net/virtio_net.c > > > +++ b/drivers/net/virtio_net.c > > > @@ -251,6 +251,12 @@ struct virtnet_info { > > > /* Does the affinity hint is set for virtqueues? */ > > > bool affinity_hint_set; > > > > > > + /* Is refill work enabled? */ > > > + bool refill_work_enabled; > > > + > > > + /* The lock to synchronize the access to refill_work_enabled */ > > > + spinlock_t refill_lock; > > > + > > > /* CPU hotplug instances for online & dead */ > > > struct hlist_node node; > > > struct hlist_node node_dead; > > > @@ -348,6 +354,20 @@ static struct page *get_a_page(struct receive_queue *rq, gfp_t gfp_mask) > > > return p; > > > } > > > > > > +static void enable_refill_work(struct virtnet_info *vi) > > > +{ > > > + spin_lock(&vi->refill_lock); > > > + vi->refill_work_enabled = true; > > > + spin_unlock(&vi->refill_lock); > > > +} > > > + > > > +static void disable_refill_work(struct virtnet_info *vi) > > > +{ > > > + spin_lock(&vi->refill_lock); > > > + vi->refill_work_enabled = false; > > > + spin_unlock(&vi->refill_lock); > > > +} > > > + > > > static void virtqueue_napi_schedule(struct napi_struct *napi, > > > struct virtqueue *vq) > > > { > > > @@ -1527,8 +1547,12 @@ static int virtnet_receive(struct receive_queue *rq, int budget, > > > } > > > > > > if (rq->vq->num_free > min((unsigned int)budget, virtqueue_get_vring_size(rq->vq)) / 2) { > > > - if (!try_fill_recv(vi, rq, GFP_ATOMIC)) > > > - schedule_delayed_work(&vi->refill, 0); > > > + if (!try_fill_recv(vi, rq, GFP_ATOMIC)) { > > > + spin_lock(&vi->refill_lock); > > > + if (vi->refill_work_enabled) > > > + schedule_delayed_work(&vi->refill, 0); > > > + spin_unlock(&vi->refill_lock); > > > + } > > > } > > > > > > u64_stats_update_begin(&rq->stats.syncp); > > > @@ -1651,6 +1675,8 @@ static int virtnet_open(struct net_device *dev) > > > struct virtnet_info *vi = netdev_priv(dev); > > > int i, err; > > > > > > + enable_refill_work(vi); > > > + > > > for (i = 0; i < vi->max_queue_pairs; i++) { > > > if (i < vi->curr_queue_pairs) > > > /* Make sure we have some buffers: if oom use wq. */ > > > @@ -2033,6 +2059,8 @@ static int virtnet_close(struct net_device *dev) > > > struct virtnet_info *vi = netdev_priv(dev); > > > int i; > > > > > > + /* Make sure NAPI doesn't schedule refill work */ > > > + disable_refill_work(vi); > > > /* Make sure refill_work doesn't re-enable napi! */ > > > cancel_delayed_work_sync(&vi->refill); > > > > > > @@ -2776,6 +2804,9 @@ static void virtnet_freeze_down(struct virtio_device *vdev) > > > netif_tx_lock_bh(vi->dev); > > > netif_device_detach(vi->dev); > > > netif_tx_unlock_bh(vi->dev); > > > + /* Make sure NAPI doesn't schedule refill work */ > > > + disable_refill_work(vi); > > > + /* Make sure refill_work doesn't re-enable napi! */ > > > cancel_delayed_work_sync(&vi->refill); > > > > > > if (netif_running(vi->dev)) { > > > @@ -2799,6 +2830,8 @@ static int virtnet_restore_up(struct virtio_device *vdev) > > > > > > virtio_device_ready(vdev); > > > > > > + enable_refill_work(vi); > > > + > > > if (netif_running(vi->dev)) { > > > for (i = 0; i < vi->curr_queue_pairs; i++) > > > if (!try_fill_recv(vi, &vi->rq[i], GFP_KERNEL)) > > > @@ -3548,6 +3581,7 @@ static int virtnet_probe(struct virtio_device *vdev) > > > vdev->priv = vi; > > > > > > INIT_WORK(&vi->config_work, virtnet_config_changed_work); > > > + spin_lock_init(&vi->refill_lock); > > > > > > /* If we can receive ANY GSO packets, we must allocate large ones. */ > > > if (virtio_has_feature(vdev, VIRTIO_NET_F_GUEST_TSO4) || > > > > > > Can't say I love all the extra state but oh well. > > I couldn't find a better way. The tricky part is that NAPI and refill > can schedule each other so we need a third state. > > ThanksI wonder whether we can add a napi flag that says going away do not schedule, and have napi_enable/napi_disable fail then.> > > > > -- > > > 2.25.1 > >