From: Jason Wang <jasowang@redhat.com>
To: mst@redhat.com, kvm@vger.kernel.org,
virtualization@lists.linux-foundation.org,
netdev@vger.kernel.org
Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, jgg@ziepe.ca,
Jason Wang <jasowang@redhat.com>
Subject: [PATCH V3 03/10] vhost: validate MMU notifier registration
Date: Wed, 7 Aug 2019 02:54:42 -0400 [thread overview]
Message-ID: <20190807065449.23373-4-jasowang@redhat.com> (raw)
In-Reply-To: <20190807065449.23373-1-jasowang@redhat.com>
The return value of mmu_notifier_register() is not checked in
vhost_vring_set_num_addr(). This will cause an out of sync between mm
and MMU notifier thus a double free. To solve this, introduce a
boolean flag to track whether MMU notifier is registered and only do
unregistering when it was true.
Reported-and-tested-by:
syzbot+e58112d71f77113ddb7b@syzkaller.appspotmail.com
Fixes: 7f466032dc9e ("vhost: access vq metadata through kernel virtual address")
Signed-off-by: Jason Wang <jasowang@redhat.com>
---
drivers/vhost/vhost.c | 19 +++++++++++++++----
drivers/vhost/vhost.h | 1 +
2 files changed, 16 insertions(+), 4 deletions(-)
diff --git a/drivers/vhost/vhost.c b/drivers/vhost/vhost.c
index 488380a581dc..17f6abea192e 100644
--- a/drivers/vhost/vhost.c
+++ b/drivers/vhost/vhost.c
@@ -629,6 +629,7 @@ void vhost_dev_init(struct vhost_dev *dev,
dev->iov_limit = iov_limit;
dev->weight = weight;
dev->byte_weight = byte_weight;
+ dev->has_notifier = false;
init_llist_head(&dev->work_list);
init_waitqueue_head(&dev->wait);
INIT_LIST_HEAD(&dev->read_list);
@@ -730,6 +731,7 @@ long vhost_dev_set_owner(struct vhost_dev *dev)
if (err)
goto err_mmu_notifier;
#endif
+ dev->has_notifier = true;
return 0;
@@ -959,7 +961,11 @@ void vhost_dev_cleanup(struct vhost_dev *dev)
}
if (dev->mm) {
#if VHOST_ARCH_CAN_ACCEL_UACCESS
- mmu_notifier_unregister(&dev->mmu_notifier, dev->mm);
+ if (dev->has_notifier) {
+ mmu_notifier_unregister(&dev->mmu_notifier,
+ dev->mm);
+ dev->has_notifier = false;
+ }
#endif
mmput(dev->mm);
}
@@ -2064,8 +2070,10 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d,
/* Unregister MMU notifer to allow invalidation callback
* can access vq->uaddrs[] without holding a lock.
*/
- if (d->mm)
+ if (d->has_notifier) {
mmu_notifier_unregister(&d->mmu_notifier, d->mm);
+ d->has_notifier = false;
+ }
vhost_uninit_vq_maps(vq);
#endif
@@ -2085,8 +2093,11 @@ static long vhost_vring_set_num_addr(struct vhost_dev *d,
if (r == 0)
vhost_setup_vq_uaddr(vq);
- if (d->mm)
- mmu_notifier_register(&d->mmu_notifier, d->mm);
+ if (d->mm) {
+ r = mmu_notifier_register(&d->mmu_notifier, d->mm);
+ if (!r)
+ d->has_notifier = true;
+ }
#endif
mutex_unlock(&vq->mutex);
diff --git a/drivers/vhost/vhost.h b/drivers/vhost/vhost.h
index 42a8c2a13ab1..a9a2a93857d2 100644
--- a/drivers/vhost/vhost.h
+++ b/drivers/vhost/vhost.h
@@ -214,6 +214,7 @@ struct vhost_dev {
int iov_limit;
int weight;
int byte_weight;
+ bool has_notifier;
};
bool vhost_exceeds_weight(struct vhost_virtqueue *vq, int pkts, int total_len);
--
2.18.1
next prev parent reply other threads:[~2019-08-07 6:55 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-07 6:54 [PATCH V3 00/10] Fixes for metadata accelreation Jason Wang
2019-08-07 6:54 ` [PATCH V3 01/10] vhost: disable metadata prefetch optimization Jason Wang
2019-08-07 7:05 ` Jason Wang
2019-08-07 6:54 ` [PATCH V3 02/10] vhost: don't set uaddr for invalid address Jason Wang
2019-08-07 6:54 ` Jason Wang [this message]
2019-08-07 6:54 ` [PATCH V3 04/10] vhost: fix vhost map leak Jason Wang
2019-08-07 6:54 ` [PATCH V3 05/10] vhost: reset invalidate_count in vhost_set_vring_num_addr() Jason Wang
2019-08-07 6:54 ` [PATCH V3 06/10] vhost: mark dirty pages during map uninit Jason Wang
2019-08-07 6:54 ` [PATCH V3 07/10] vhost: don't do synchronize_rcu() in vhost_uninit_vq_maps() Jason Wang
2019-08-07 6:54 ` [PATCH V3 08/10] vhost: do not use RCU to synchronize MMU notifier with worker Jason Wang
2019-08-07 6:54 ` [PATCH V3 09/10] vhost: correctly set dirty pages in MMU notifiers callback Jason Wang
2019-08-07 6:54 ` [PATCH V3 10/10] vhost: do not return -EAGAIN for non blocking invalidation too early Jason Wang
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