nci_rf_discover_ntf_packet() and nci_rf_intf_activated_ntf_packet() each parse a notification into an on-stack struct (nci_rf_discover_ntf / nci_rf_intf_activated_ntf) that is not initialised. The technology- and activation-specific parameters are only extracted when the corresponding length field is non-zero, so a notification that reports a zero length leaves the relevant union uninitialised - and the handlers then read it: - discover: with rf_tech_specific_params_len == 0, nci_add_new_protocol() reads the uninitialised rf_tech_specific_params union (nfca_poll-> nfcid1_len is used as a branch condition and a memcpy length) into ndev->targets; - activated: with rf_tech_specific_params_len == 0 the same union is read via nci_target_auto_activated(); with activation_params_len == 0 the activation_params union is read by nci_store_ats_nfc_iso_dep() into ndev->target_ats. In each case the uninitialised bytes are subsequently exposed to user space (NFC_CMD_GET_TARGET / NFC_ATTR_TARGET_ATS). BUG: KMSAN: uninit-value in nci_add_new_protocol+0x624/0x6c0 nci_add_new_protocol+0x624/0x6c0 nci_ntf_packet+0x25b2/0x3c30 nci_rx_work+0x318/0x5d0 process_scheduled_works+0x84b/0x17a0 worker_thread+0xc10/0x11b0 kthread+0x376/0x500 Local variable ntf.i created at: nci_ntf_packet+0xbc2/0x3c30 Zero-initialise both on-stack notifications so the unions read back as zero when the corresponding parameters are absent. Fixes: 019c4fbaa790 ("NFC: Add NCI multiple targets support") Fixes: e8c0dacd9836 ("NFC: Update names and structs to NCI spec 1.0 d18") Link: https://lore.kernel.org/netdev/20260623172109.1105965-2-horms@kernel.org/ Cc: stable@vger.kernel.org Assisted-by: Bynario AI Signed-off-by: Samuel Page --- net/nfc/nci/ntf.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/nfc/nci/ntf.c b/net/nfc/nci/ntf.c index c96512bb8653..274d9a4202c9 100644 --- a/net/nfc/nci/ntf.c +++ b/net/nfc/nci/ntf.c @@ -440,7 +440,7 @@ void nci_clear_target_list(struct nci_dev *ndev) static int nci_rf_discover_ntf_packet(struct nci_dev *ndev, const struct sk_buff *skb) { - struct nci_rf_discover_ntf ntf; + struct nci_rf_discover_ntf ntf = {}; const __u8 *data; bool add_target = true; @@ -688,7 +688,7 @@ static int nci_rf_intf_activated_ntf_packet(struct nci_dev *ndev, const struct sk_buff *skb) { struct nci_conn_info *conn_info; - struct nci_rf_intf_activated_ntf ntf; + struct nci_rf_intf_activated_ntf ntf = {}; const __u8 *data; int err = NCI_STATUS_OK; base-commit: a986fde914d88af47eb78fd29c5d1af7952c3500 -- 2.54.0