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Sun, 12 Apr 2026 19:43:42 -0700 (PDT) From: Ashutosh Desai To: netdev@vger.kernel.org Cc: kuba@kernel.org, edumazet@google.com, davem@davemloft.net, pabeni@redhat.com, horms@kernel.org, linux-kernel@vger.kernel.org, Ashutosh Desai Subject: [PATCH v3] nfc: hci: fix out-of-bounds read in HCP header parsing Date: Mon, 13 Apr 2026 02:43:29 +0000 Message-Id: <20260413024329.3293075-1-ashutoshdesai993@gmail.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20260413000627.3273477-1-ashutoshdesai993@gmail.com> References: <20260413000627.3273477-1-ashutoshdesai993@gmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" nfc_hci_recv_from_llc() and nci_hci_data_received_cb() cast skb->data to struct hcp_packet and read the message header byte without checking that enough data is present in the linear sk_buff area. A malicious NFC peer can send a 1-byte HCP frame that passes through the SHDLC layer and reaches these functions, causing an out-of-bounds heap read. Fix this by adding pskb_may_pull() before each cast to ensure the full 2-byte HCP header is pulled into the linear area before it is accessed. Signed-off-by: Ashutosh Desai --- v3: drop redundant pskb_may_pull checks from msg_rx_work functions, remove incorrect Suggested-by tag v2: switch skb->len check to pskb_may_pull net/nfc/hci/core.c | 5 +++++ net/nfc/nci/hci.c | 5 +++++ 2 files changed, 10 insertions(+) diff --git a/net/nfc/hci/core.c b/net/nfc/hci/core.c index 0d33c81a1..cd9cf6c94 100644 --- a/net/nfc/hci/core.c +++ b/net/nfc/hci/core.c @@ -904,6 +904,11 @@ 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 =3D (struct hcp_packet *)hcp_skb->data; type =3D HCP_MSG_GET_TYPE(packet->message.header); if (type =3D=3D NFC_HCI_HCP_RESPONSE) { diff --git a/net/nfc/nci/hci.c b/net/nfc/nci/hci.c index 40ae8e5a7..6e633da25 100644 --- a/net/nfc/nci/hci.c +++ b/net/nfc/nci/hci.c @@ -482,6 +482,11 @@ 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 =3D (struct nci_hcp_packet *)hcp_skb->data; type =3D NCI_HCP_MSG_GET_TYPE(packet->message.header); if (type =3D=3D NCI_HCI_HCP_RESPONSE) { --=20 2.34.1