[PATCH 6.6 168/567] net: nfc: nci: Fix zero-length proprietary notifications

Greg Kroah-Hartman
2026-03-23T14:59:56Z

6.6-stable review patch. If anyone has any objections, please let me know.

------------------

From: Ian Ray <ian.ray@gehealthcare.com>

[ Upstream commit f7d92f11bd33a6eb49c7c812255ef4ab13681f0f ]

NCI NFC controllers may have proprietary OIDs with zero-length payload.
One example is: drivers/nfc/nxp-nci/core.c, NXP_NCI_RF_TXLDO_ERROR_NTF.

Allow a zero length payload in proprietary notifications *only*.

Before:

-- >8 --
kernel: nci: nci_recv_frame: len 3
-- >8 --

After:

-- >8 --
kernel: nci: nci_recv_frame: len 3
kernel: nci: nci_ntf_packet: NCI RX: MT=ntf, PBF=0, GID=0x1, OID=0x23, plen=0
kernel: nci: nci_ntf_packet: unknown ntf opcode 0x123
kernel: nfc nfc0: NFC: RF transmitter couldn't start. Bad power and/or configuration?
-- >8 --

After fixing the hardware:

-- >8 --
kernel: nci: nci_recv_frame: len 27
kernel: nci: nci_ntf_packet: NCI RX: MT=ntf, PBF=0, GID=0x1, OID=0x5, plen=24
kernel: nci: nci_rf_intf_activated_ntf_packet: rf_discovery_id 1
-- >8 --

Fixes: d24b03535e5e ("nfc: nci: Fix uninit-value in nci_dev_up and nci_ntf_packet")
Signed-off-by: Ian Ray <ian.ray@gehealthcare.com>
Link: https://patch.msgid.link/20260302163238.140576-1-ian.ray@gehealthcare.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/nfc/nci/core.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/net/nfc/nci/core.c b/net/nfc/nci/core.c
index b7d4952a7dcf8..7a4742a092626 100644
--- a/net/nfc/nci/core.c
+++ b/net/nfc/nci/core.c
@@ -1471,10 +1471,20 @@ static bool nci_valid_size(struct sk_buff *skb)
unsigned int hdr_size = NCI_CTRL_HDR_SIZE;

if (skb->len < hdr_size ||
- !nci_plen(skb->data) ||
skb->len < hdr_size + nci_plen(skb->data)) {
return false;
}
+
+ if (!nci_plen(skb->data)) {
+ /* Allow zero length in proprietary notifications (0x20 - 0x3F). */
+ if (nci_opcode_oid(nci_opcode(skb->data)) >= 0x20 &&
+ nci_mt(skb->data) == NCI_MT_NTF_PKT)
+ return true;
+
+ /* Disallow zero length otherwise. */
+ return false;
+ }
+
return true;
}

--
2.51.0