[Devel] [PATCH RHEL7 COMMIT] ms/vsock: avoid to assign transport if its initialization fails

[Vasily Averin]

The commit is pushed to "branch-rh7-3.10.0-1160.21.1.vz7.174.x-ovz" and will appear at https://src.openvz.org/scm/ovz/vzkernel.git
after rh7-3.10.0-1160.21.1.vz7.174.11
------>
commit c85d7d7c4097911c8a7660ed0e61033d1348edf5
Author: Stefano Garzarella <sgarzare at redhat.com>
Date:   Thu Apr 22 03:41:49 2021 +0300

    ms/vsock: avoid to assign transport if its initialization fails
    
    If transport->init() fails, we can't assign the transport to the
    socket, because it's not initialized correctly, and any future
    calls to the transport callbacks would have an unexpected behavior.
    
    Fixes: c0cfa2d8a788 ("vsock: add multi-transports support")
    Reported-and-tested-by: syzbot+e2e5c07bf353b2f79daa at syzkaller.appspotmail.com
    Signed-off-by: Stefano Garzarella <sgarzare at redhat.com>
    Reviewed-by: Jorgen Hansen <jhansen at vmware.com>
    Signed-off-by: David S. Miller <davem at davemloft.net>
    
    https://jira.sw.ru/browse/PSBM-128702
    (cherry picked from commit 039fcccaed338b2ff6587178c1219c1ef383a1d9)
    Signed-off-by: Konstantin Khorenko <khorenko at virtuozzo.com>
---
 net/vmw_vsock/af_vsock.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/net/vmw_vsock/af_vsock.c b/net/vmw_vsock/af_vsock.c
index ff1b2cdef..cc69c6a 100644
--- a/net/vmw_vsock/af_vsock.c
+++ b/net/vmw_vsock/af_vsock.c
@@ -441,6 +441,7 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
 	const struct vsock_transport *new_transport;
 	struct sock *sk = sk_vsock(vsk);
 	unsigned int remote_cid = vsk->remote_addr.svm_cid;
+	int ret;
 
 	switch (sk->sk_type) {
 	case SOCK_DGRAM:
@@ -472,9 +473,15 @@ int vsock_assign_transport(struct vsock_sock *vsk, struct vsock_sock *psk)
 	if (!new_transport || !try_module_get(new_transport->module))
 		return -ENODEV;
 
+	ret = new_transport->init(vsk, psk);
+	if (ret) {
+		module_put(new_transport->module);
+		return ret;
+	}
+
 	vsk->transport = new_transport;
 
-	return vsk->transport->init(vsk, psk);
+	return 0;
 }
 EXPORT_SYMBOL_GPL(vsock_assign_transport);