diff --git a/net/nfc/llcp_core.c b/net/nfc/llcp_core.c index 1dac28136e6a..0ae89ab42aaa 100644 --- a/net/nfc/llcp_core.c +++ b/net/nfc/llcp_core.c @@ -145,6 +145,13 @@ static void nfc_llcp_socket_release(struct nfc_llcp_local *local, bool device, static struct nfc_llcp_local *nfc_llcp_local_get(struct nfc_llcp_local *local) { + /* Since using nfc_llcp_local may result in usage of nfc_dev, whenever + * we hold a reference to local, we also need to hold a reference to + * the device to avoid UAF. + */ + if (!nfc_get_device(local->dev->idx)) + return NULL; + kref_get(&local->ref); return local; @@ -177,10 +184,18 @@ static void local_release(struct kref *ref) int nfc_llcp_local_put(struct nfc_llcp_local *local) { + struct nfc_dev *dev; + int ret; + if (local == NULL) return 0; - return kref_put(&local->ref, local_release); + dev = local->dev; + + ret = kref_put(&local->ref, local_release); + nfc_put_device(dev); + + return ret; } static struct nfc_llcp_sock *nfc_llcp_sock_get(struct nfc_llcp_local *local, @@ -930,9 +945,7 @@ static void nfc_llcp_recv_connect(struct nfc_llcp_local *local, if (sk_acceptq_is_full(parent)) { reason = LLCP_DM_REJ; - release_sock(&sock->sk); - sock_put(&sock->sk); - goto fail; + goto fail_put_sock; } if (sock->ssap == LLCP_SDP_UNBOUND) { @@ -942,9 +955,7 @@ static void nfc_llcp_recv_connect(struct nfc_llcp_local *local, if (ssap == LLCP_SAP_MAX) { reason = LLCP_DM_REJ; - release_sock(&sock->sk); - sock_put(&sock->sk); - goto fail; + goto fail_put_sock; } sock->ssap = ssap; @@ -953,14 +964,18 @@ static void nfc_llcp_recv_connect(struct nfc_llcp_local *local, new_sk = nfc_llcp_sock_alloc(NULL, parent->sk_type, GFP_ATOMIC, 0); if (new_sk == NULL) { reason = LLCP_DM_REJ; - release_sock(&sock->sk); - sock_put(&sock->sk); - goto fail; + goto fail_put_sock; } new_sock = nfc_llcp_sock(new_sk); - new_sock->dev = local->dev; + new_sock->local = nfc_llcp_local_get(local); + if (!new_sock->local) { + reason = LLCP_DM_REJ; + goto fail_free_new_sock; + } + + new_sock->dev = local->dev; new_sock->rw = sock->rw; new_sock->miux = sock->miux; new_sock->nfc_protocol = sock->nfc_protocol; @@ -1004,8 +1019,13 @@ static void nfc_llcp_recv_connect(struct nfc_llcp_local *local, return; +fail_free_new_sock: + sock_put(&new_sock->sk); + nfc_llcp_sock_free(new_sock); +fail_put_sock: + release_sock(&sock->sk); + sock_put(&sock->sk); fail: - /* Send DM */ nfc_llcp_send_dm(local, dsap, ssap, reason); } @@ -1597,7 +1617,16 @@ int nfc_llcp_register_device(struct nfc_dev *ndev) if (local == NULL) return -ENOMEM; - local->dev = ndev; + /* As we are going to initialize local's refcount, we need to get the + * nfc_dev to avoid UAF, otherwise there is no point in continuing. + * See nfc_llcp_local_get(). + */ + local->dev = nfc_get_device(ndev->idx); + if (!local->dev) { + kfree(local); + return -ENODEV; + } + INIT_LIST_HEAD(&local->list); kref_init(&local->ref); mutex_init(&local->sdp_lock);