From: Zha Bin zhabin@linux.alibaba.com

commit 7fbe078c37aba3088359c9256c1a1d0c3e39ee81 upstream.

Backport from 5.0 tree, with diff hunk adjusted.

The vsock core only supports 32bit CID, but the Virtio-vsock spec define CID (dst_cid and src_cid) as u64 and the upper 32bits is reserved as zero. This inconsistency causes one bug in vhost vsock driver. The scenarios is:

0. A hash table (vhost_vsock_hash) is used to map an CID to a vsock object. And hash_min() is used to compute the hash key. hash_min() is defined as: (sizeof(val) <= 4 ? hash_32(val, bits) : hash_long(val, bits)). That means the hash algorithm has dependency on the size of macro argument 'val'. 0. In function vhost_vsock_set_cid(), a 64bit CID is passed to hash_min() to compute the hash key when inserting a vsock object into the hash table. 0. In function vhost_vsock_get(), a 32bit CID is passed to hash_min() to compute the hash key when looking up a vsock for an CID.

Because the different size of the CID, hash_min() returns different hash key, thus fails to look up the vsock object for an CID.

To fix this bug, we keep CID as u64 in the IOCTLs and virtio message headers, but explicitly convert u64 to u32 when deal with the hash table and vsock core.

Fixes: 834e772c8db0 ("vhost/vsock: fix use-after-free in network stack callers") Link: https://github.com/stefanha/virtio/blob/vsock/trunk/content.tex Signed-off-by: Zha Bin zhabin@linux.alibaba.com Reviewed-by: Liu Jiang gerry@linux.alibaba.com Reviewed-by: Stefan Hajnoczi stefanha@redhat.com Acked-by: Jason Wang jasowang@redhat.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Shengjing Zhu i@zhsj.me --- drivers/vhost/vsock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c index fa93f6711d8d..e440f87ae1d6 100644 --- a/drivers/vhost/vsock.c +++ b/drivers/vhost/vsock.c @@ -642,7 +642,7 @@ static int vhost_vsock_set_cid(struct vhost_vsock *vsock, u64 guest_cid) hash_del_rcu(&vsock->hash);

vsock->guest_cid = guest_cid; - hash_add_rcu(vhost_vsock_hash, &vsock->hash, guest_cid); + hash_add_rcu(vhost_vsock_hash, &vsock->hash, vsock->guest_cid); spin_unlock_bh(&vhost_vsock_lock);

return 0;