Re: [PATCH net V4] virtio-net: fix the race between refill work and close
On Mon, Jul 4, 2022 at 3:03 PM Michael S. Tsirkin wrote:
>
> On Mon, Jul 04, 2022 at 02:32:45PM +0800, Jason Wang wrote:
> > On Mon, Jul 4, 2022 at 2:19 PM Michael S. Tsirkin wrote:
> > >
> > > On Mon, Jul 04, 2022 at 12:19:48PM +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 source
> > > > of the refill work scheduling. This means an NAPI poll callback 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 88810562c92e 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:
> > > >
> > > > 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
> > > >
> > > > ...
> > > >
> > > > Fixes: b2baed69e605c ("virtio_net: set/cancel work on
> > > > ndo_open/ndo_stop")
> > > > Signed-off-by: Jason Wang
> > > > ---
> > > > Changes since V3:
> > > > - rebase to -net
> > > > Changes since V2:
> > > > - use spin_unlock()/lock_bh() in open/stop to synchronize with bh
> > > > Changes since V1:
> > > > - Tweak the changelog
> > > > ---
> > > > drivers/net/virtio_net.c | 35 +--
> > > > 1 file changed, 33 insertions(+), 2 deletions(-)
> > > >
> > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > > index 356cf8dd4164..68430d7923ac 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? */
> > >
> > > refilling enabled
> >
> > I think it should be reill work, we try refill first, if fail we
> > schedule the work:
> >
> > if (!try_fill_recv(vi, rq, GFP_ATOMIC))
> > schedule_delayed_work(>refill, 0);
> >
> > Thanks
>
> maybe "delayed refill"? It's not "work" it's a work struct.
> I'm trying to be consistent with:
> /* Work struct for refilling if we run low on memory. */
> struct delayed_work refill;
Ok, that's fine.
Will post a new version.
Thanks
>
>
> > >
> > > > + bool refill_work_enabled;
> > >
> > >
> > > refill_work -> refill?
> > >
> > > > +
> > > > + /* The lock to synchronize the access to refill_work_enabled */
> > >
> > > .. and refill
> > >
> > > And maybe put these field near the refill field.
> > >
> > > > + 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_bh(>refill_lock);
> > > > + vi->refill_work_enabled = true;
> > > > + spin_unlock_bh(>refill_lock);
> > > > +}
> > > > +
> > > > +static void disable_refill_work(struct virtnet_info *vi)
> > > > +{
> > > > + spin_lock_bh(>refill_lock);
> > > > + vi->refill_work_enabled = false;
> > > > + spin_unlock_bh(>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(>refill, 0);
> > > > + if (!try_fill_recv(vi, rq, GFP_ATOMIC)) {
> > > > + spin_lock(>refill_lock);
> > >
Re: [PATCH net V4] virtio-net: fix the race between refill work and close
On Mon, Jul 04, 2022 at 02:32:45PM +0800, Jason Wang wrote:
> On Mon, Jul 4, 2022 at 2:19 PM Michael S. Tsirkin wrote:
> >
> > On Mon, Jul 04, 2022 at 12:19:48PM +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 source
> > > of the refill work scheduling. This means an NAPI poll callback 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 88810562c92e 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:
> > >
> > > 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
> > >
> > > ...
> > >
> > > Fixes: b2baed69e605c ("virtio_net: set/cancel work on ndo_open/ndo_stop")
> > > Signed-off-by: Jason Wang
> > > ---
> > > Changes since V3:
> > > - rebase to -net
> > > Changes since V2:
> > > - use spin_unlock()/lock_bh() in open/stop to synchronize with bh
> > > Changes since V1:
> > > - Tweak the changelog
> > > ---
> > > drivers/net/virtio_net.c | 35 +--
> > > 1 file changed, 33 insertions(+), 2 deletions(-)
> > >
> > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > > index 356cf8dd4164..68430d7923ac 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? */
> >
> > refilling enabled
>
> I think it should be reill work, we try refill first, if fail we
> schedule the work:
>
> if (!try_fill_recv(vi, rq, GFP_ATOMIC))
> schedule_delayed_work(>refill, 0);
>
> Thanks
maybe "delayed refill"? It's not "work" it's a work struct.
I'm trying to be consistent with:
/* Work struct for refilling if we run low on memory. */
struct delayed_work refill;
> >
> > > + bool refill_work_enabled;
> >
> >
> > refill_work -> refill?
> >
> > > +
> > > + /* The lock to synchronize the access to refill_work_enabled */
> >
> > .. and refill
> >
> > And maybe put these field near the refill field.
> >
> > > + 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_bh(>refill_lock);
> > > + vi->refill_work_enabled = true;
> > > + spin_unlock_bh(>refill_lock);
> > > +}
> > > +
> > > +static void disable_refill_work(struct virtnet_info *vi)
> > > +{
> > > + spin_lock_bh(>refill_lock);
> > > + vi->refill_work_enabled = false;
> > > + spin_unlock_bh(>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(>refill, 0);
> > > + if (!try_fill_recv(vi, rq, GFP_ATOMIC)) {
> > > + spin_lock(>refill_lock);
> > > + if (vi->refill_work_enabled)
> > > + schedule_delayed_work(>refill, 0);
> > > + spin_unlock(>refill_lock);
> > > + }
> > > }
> > >
> > > u64_stats_update_begin(>stats.syncp);
> > > @@ -1651,6 +1675,8 @@ static int virtnet_open(struct net_device *dev)
> > > struct virtnet_info
Re: [PATCH net V4] virtio-net: fix the race between refill work and close
On Mon, Jul 4, 2022 at 2:19 PM Michael S. Tsirkin wrote:
>
> On Mon, Jul 04, 2022 at 12:19:48PM +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 source
> > of the refill work scheduling. This means an NAPI poll callback 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 88810562c92e 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:
> >
> > 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
> >
> > ...
> >
> > Fixes: b2baed69e605c ("virtio_net: set/cancel work on ndo_open/ndo_stop")
> > Signed-off-by: Jason Wang
> > ---
> > Changes since V3:
> > - rebase to -net
> > Changes since V2:
> > - use spin_unlock()/lock_bh() in open/stop to synchronize with bh
> > Changes since V1:
> > - Tweak the changelog
> > ---
> > drivers/net/virtio_net.c | 35 +--
> > 1 file changed, 33 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> > index 356cf8dd4164..68430d7923ac 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? */
>
> refilling enabled
I think it should be reill work, we try refill first, if fail we
schedule the work:
if (!try_fill_recv(vi, rq, GFP_ATOMIC))
schedule_delayed_work(>refill, 0);
Thanks
>
> > + bool refill_work_enabled;
>
>
> refill_work -> refill?
>
> > +
> > + /* The lock to synchronize the access to refill_work_enabled */
>
> .. and refill
>
> And maybe put these field near the refill field.
>
> > + 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_bh(>refill_lock);
> > + vi->refill_work_enabled = true;
> > + spin_unlock_bh(>refill_lock);
> > +}
> > +
> > +static void disable_refill_work(struct virtnet_info *vi)
> > +{
> > + spin_lock_bh(>refill_lock);
> > + vi->refill_work_enabled = false;
> > + spin_unlock_bh(>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(>refill, 0);
> > + if (!try_fill_recv(vi, rq, GFP_ATOMIC)) {
> > + spin_lock(>refill_lock);
> > + if (vi->refill_work_enabled)
> > + schedule_delayed_work(>refill, 0);
> > + spin_unlock(>refill_lock);
> > + }
> > }
> >
> > u64_stats_update_begin(>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);
> >
Re: [PATCH net V4] virtio-net: fix the race between refill work and close
On Mon, Jul 04, 2022 at 12:19:48PM +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 source
> of the refill work scheduling. This means an NAPI poll callback 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 88810562c92e 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:
>
> 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
>
> ...
>
> Fixes: b2baed69e605c ("virtio_net: set/cancel work on ndo_open/ndo_stop")
> Signed-off-by: Jason Wang
> ---
> Changes since V3:
> - rebase to -net
> Changes since V2:
> - use spin_unlock()/lock_bh() in open/stop to synchronize with bh
> Changes since V1:
> - Tweak the changelog
> ---
> drivers/net/virtio_net.c | 35 +--
> 1 file changed, 33 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c
> index 356cf8dd4164..68430d7923ac 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? */
refilling enabled
> + bool refill_work_enabled;
refill_work -> refill?
> +
> + /* The lock to synchronize the access to refill_work_enabled */
.. and refill
And maybe put these field near the refill field.
> + 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_bh(>refill_lock);
> + vi->refill_work_enabled = true;
> + spin_unlock_bh(>refill_lock);
> +}
> +
> +static void disable_refill_work(struct virtnet_info *vi)
> +{
> + spin_lock_bh(>refill_lock);
> + vi->refill_work_enabled = false;
> + spin_unlock_bh(>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(>refill, 0);
> + if (!try_fill_recv(vi, rq, GFP_ATOMIC)) {
> + spin_lock(>refill_lock);
> + if (vi->refill_work_enabled)
> + schedule_delayed_work(>refill, 0);
> + spin_unlock(>refill_lock);
> + }
> }
>
> u64_stats_update_begin(>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(>refill);
>
> @@ -2792,6 +2820,8 @@ static int virtnet_restore_up(struct virtio_device
> *vdev)
>
> virtio_device_ready(vdev);
>
> + enable_refill_work(vi);
> +
> if (netif_running(vi->dev)) {
> err = virtnet_open(vi->dev);
> if (err)
> @@ -3535,6 +3565,7 @@ static int virtnet_probe(struct virtio_device *vdev)
> vdev->priv = vi;
>
> INIT_WORK(>config_work,
