nfc: hci: fix out-of-bounds read in HCP header parsing

Both nfc_hci_recv_from_llc() and nci_hci_data_received_cb() read
packet->header from skb->data at function entry without first checking
that the buffer holds at least one byte. A malicious NFC peer can send
a 0-byte HCP frame that passes through the SHDLC layer and reaches
these functions, causing an out-of-bounds heap read of packet->header.
The same 0-byte frame, if queued as a non-final fragment, also causes
the reassembly loop to underflow msg_len to UINT_MAX, triggering
skb_over_panic() when the reassembled skb is written.

Fix this by adding a pskb_may_pull() check at the entry of each
function before packet->header is first accessed. The existing
pskb_may_pull() checks before the reassembled hcp_skb is cast to
struct hcp_packet remain in place to guard the 2-byte HCP message
header.

Fixes: 8b8d2e08bf0d ("NFC: HCI support")
Fixes: 11f54f228643 ("NFC: nci: Add HCI over NCI protocol support")
Cc: stable@vger.kernel.org
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: Ashutosh Desai <ashutoshdesai993@gmail.com>
Link: https://patch.msgid.link/20260505170712.96560-1-ashutoshdesai993@gmail.com
Signed-off-by: David Heidelberg <david@ixit.cz>

diff --git a/net/nfc/hci/core.c b/net/nfc/hci/core.c
index 0d33c81a15fe12aa7021038b2fc01f43c12ff342..ba6f0310ffd7cd747d93de25994c3128da469a82 100644 (file)
--- a/net/nfc/hci/core.c
+++ b/net/nfc/hci/core.c
@@ -861,6 +861,11 @@ static void nfc_hci_recv_from_llc(struct nfc_hci_dev *hdev, struct sk_buff *skb)
        struct sk_buff *frag_skb;
        int msg_len;
 
+       if (!pskb_may_pull(skb, NFC_HCI_HCP_PACKET_HEADER_LEN)) {
+               kfree_skb(skb);
+               return;
+       }
+
        packet = (struct hcp_packet *)skb->data;
        if ((packet->header & ~NFC_HCI_FRAGMENT) == 0) {
                skb_queue_tail(&hdev->rx_hcp_frags, skb);
@@ -904,6 +909,11 @@ static void nfc_hci_recv_from_llc(struct nfc_hci_dev *hdev, struct sk_buff *skb)
         * unblock waiting cmd context. Otherwise, enqueue to dispatch
         * in separate context where handler can also execute command.
         */
+       if (!pskb_may_pull(hcp_skb, NFC_HCI_HCP_HEADER_LEN)) {
+               kfree_skb(hcp_skb);
+               return;
+       }
+
        packet = (struct hcp_packet *)hcp_skb->data;
        type = HCP_MSG_GET_TYPE(packet->message.header);
        if (type == NFC_HCI_HCP_RESPONSE) {

diff --git a/net/nfc/nci/hci.c b/net/nfc/nci/hci.c
index 40ae8e5a7ec7a768110fa9c845e7f14a808d1d02..c03e8a0bd3bd641d1209dbf06f6e73b981244fa7 100644 (file)
--- a/net/nfc/nci/hci.c
+++ b/net/nfc/nci/hci.c
@@ -439,6 +439,11 @@ void nci_hci_data_received_cb(void *context,
                return;
        }
 
+       if (!pskb_may_pull(skb, NCI_HCI_HCP_PACKET_HEADER_LEN)) {
+               kfree_skb(skb);
+               return;
+       }
+
        packet = (struct nci_hcp_packet *)skb->data;
        if ((packet->header & ~NCI_HCI_FRAGMENT) == 0) {
                skb_queue_tail(&ndev->hci_dev->rx_hcp_frags, skb);
@@ -482,6 +487,11 @@ void nci_hci_data_received_cb(void *context,
         * unblock waiting cmd context. Otherwise, enqueue to dispatch
         * in separate context where handler can also execute command.
         */
+       if (!pskb_may_pull(hcp_skb, NCI_HCI_HCP_HEADER_LEN)) {
+               kfree_skb(hcp_skb);
+               return;
+       }
+
        packet = (struct nci_hcp_packet *)hcp_skb->data;
        type = NCI_HCP_MSG_GET_TYPE(packet->message.header);
        if (type == NCI_HCI_HCP_RESPONSE) {