This feature bit is duplicated with VIRTIO_F_ANY_LAYOUT, this means if
a userpsace want to enable VRITIO_F_ANY_LAYOUT,
VHOST_NET_F_VIRTIO_NET_HDR will be implied too. This is wrong and will
break networking. Fixing this by safely removing
VHOST_NET_F_VIRTIO_NET_HDR support. There should be very few or even
no userspace can use this. Further cleanups could be done for
-net-next for safety.

In the future, we need a vhost dedicated feature set/get ioctl()
instead of reusing virtio ones.

Fixes: 4e9fa50c6ccbe ("vhost: move features to core")
Signed-off-by: Jason Wang <[email protected]>
---
 drivers/vhost/net.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/vhost/net.c b/drivers/vhost/net.c
index 986058a..83eef52 100644
--- a/drivers/vhost/net.c
+++ b/drivers/vhost/net.c
@@ -69,7 +69,6 @@ MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
 
 enum {
        VHOST_NET_FEATURES = VHOST_FEATURES |
-                        (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
                         (1ULL << VIRTIO_NET_F_MRG_RXBUF) |
                         (1ULL << VIRTIO_F_IOMMU_PLATFORM)
 };
@@ -1255,15 +1254,11 @@ static int vhost_net_set_features(struct vhost_net *n, 
u64 features)
                               (1ULL << VIRTIO_F_VERSION_1))) ?
                        sizeof(struct virtio_net_hdr_mrg_rxbuf) :
                        sizeof(struct virtio_net_hdr);
-       if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
-               /* vhost provides vnet_hdr */
-               vhost_hlen = hdr_len;
-               sock_hlen = 0;
-       } else {
-               /* socket provides vnet_hdr */
-               vhost_hlen = 0;
-               sock_hlen = hdr_len;
-       }
+
+        /* socket provides vnet_hdr */
+       vhost_hlen = 0;
+       sock_hlen = hdr_len;
+
        mutex_lock(&n->dev.mutex);
        if ((features & (1 << VHOST_F_LOG_ALL)) &&
            !vhost_log_access_ok(&n->dev))
-- 
2.7.4

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