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authorIlya Maximets <i.maximets@samsung.com>2019-07-08 14:03:44 +0300
committerDaniel Borkmann <daniel@iogearbox.net>2019-07-12 15:02:21 +0200
commit5464c3a0e9a037b63d5229cdea08dddc01a98aac (patch)
treeb7d54d9aef6b6e95b7db08ad745aa5345b4a856f /net
parent675716400da6f15b9d3db04ef74ee74ca9a00af3 (diff)
downloadlinux-5464c3a0e9a037b63d5229cdea08dddc01a98aac.tar.bz2
xdp: fix potential deadlock on socket mutex
There are 2 call chains: a) xsk_bind --> xdp_umem_assign_dev b) unregister_netdevice_queue --> xsk_notifier with the following locking order: a) xs->mutex --> rtnl_lock b) rtnl_lock --> xdp.lock --> xs->mutex Different order of taking 'xs->mutex' and 'rtnl_lock' could produce a deadlock here. Fix that by moving the 'rtnl_lock' before 'xs->lock' in the bind call chain (a). Reported-by: syzbot+bf64ec93de836d7f4c2c@syzkaller.appspotmail.com Fixes: 455302d1c9ae ("xdp: fix hang while unregistering device bound to xdp socket") Signed-off-by: Ilya Maximets <i.maximets@samsung.com> Acked-by: Jonathan Lemon <jonathan.lemon@gmail.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Diffstat (limited to 'net')
-rw-r--r--net/xdp/xdp_umem.c16
-rw-r--r--net/xdp/xsk.c2
2 files changed, 8 insertions, 10 deletions
diff --git a/net/xdp/xdp_umem.c b/net/xdp/xdp_umem.c
index 20c91f02d3d8..83de74ca729a 100644
--- a/net/xdp/xdp_umem.c
+++ b/net/xdp/xdp_umem.c
@@ -87,21 +87,20 @@ int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
struct netdev_bpf bpf;
int err = 0;
+ ASSERT_RTNL();
+
force_zc = flags & XDP_ZEROCOPY;
force_copy = flags & XDP_COPY;
if (force_zc && force_copy)
return -EINVAL;
- rtnl_lock();
- if (xdp_get_umem_from_qid(dev, queue_id)) {
- err = -EBUSY;
- goto out_rtnl_unlock;
- }
+ if (xdp_get_umem_from_qid(dev, queue_id))
+ return -EBUSY;
err = xdp_reg_umem_at_qid(dev, umem, queue_id);
if (err)
- goto out_rtnl_unlock;
+ return err;
umem->dev = dev;
umem->queue_id = queue_id;
@@ -110,7 +109,7 @@ int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
if (force_copy)
/* For copy-mode, we are done. */
- goto out_rtnl_unlock;
+ return 0;
if (!dev->netdev_ops->ndo_bpf ||
!dev->netdev_ops->ndo_xsk_async_xmit) {
@@ -125,7 +124,6 @@ int xdp_umem_assign_dev(struct xdp_umem *umem, struct net_device *dev,
err = dev->netdev_ops->ndo_bpf(dev, &bpf);
if (err)
goto err_unreg_umem;
- rtnl_unlock();
umem->zc = true;
return 0;
@@ -135,8 +133,6 @@ err_unreg_umem:
err = 0; /* fallback to copy mode */
if (err)
xdp_clear_umem_at_qid(dev, queue_id);
-out_rtnl_unlock:
- rtnl_unlock();
return err;
}
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index b994c32a664a..59b57d708697 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -430,6 +430,7 @@ static int xsk_bind(struct socket *sock, struct sockaddr *addr, int addr_len)
if (flags & ~(XDP_SHARED_UMEM | XDP_COPY | XDP_ZEROCOPY))
return -EINVAL;
+ rtnl_lock();
mutex_lock(&xs->mutex);
if (xs->state != XSK_READY) {
err = -EBUSY;
@@ -515,6 +516,7 @@ out_unlock:
xs->state = XSK_BOUND;
out_release:
mutex_unlock(&xs->mutex);
+ rtnl_unlock();
return err;
}