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Mon, 13 Jul 2026 14:59:40 -0700 (PDT) Received: from PeakBook-Mini.tail8e484.ts.net ([178.197.218.188]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-4950a2f9402sm28390785e9.13.2026.07.13.14.59.37 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 13 Jul 2026 14:59:39 -0700 (PDT) From: Doruk Tan Ozturk To: David Heidelberg Cc: oe-linux-nfc@lists.linux.dev, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH net] nfc: microread: validate CARD_FOUND event length before parsing targets Date: Mon, 13 Jul 2026 23:59:36 +0200 Message-ID: <20260713215936.23137-1-doruk@0sec.ai> X-Mailer: git-send-email 2.53.0 Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit microread_target_discovered() parses a device-supplied MREAD_CARD_FOUND event into a struct nfc_target, reading fixed offsets and -- for the ISO-A and ISO-A-3 gates -- a variable-length NFCID1 straight out of the event skb. The only length check is nfcid1_len vs sizeof(targets->nfcid1); skb->len itself is never validated, so a short event makes every gate case read out of bounds past the skb: - ISO-A / ISO-A-3: fixed ATQA/SAK/LEN reads plus a memcpy of an attacker-controlled nfcid1_len bytes from the NFCID1 offset; - ISO-B / NFC-T1 / NFC-T3: a fixed 4- or 8-byte NFCID1 memcpy from a fixed offset. The copied nfcid1 is exported to user space via nfc_targets_found(), so the over-read is an information leak (and a possible oops on an unmapped page). Reject events too short for the fields each gate case reads. Found by 0sec (https://0sec.ai). Fixes: cfad1ba87150 ("NFC: Initial support for Inside Secure microread") Cc: stable@vger.kernel.org Assisted-by: 0sec Signed-off-by: Doruk Tan Ozturk --- drivers/nfc/microread/microread.c | 31 +++++++++++++++++++++++++++++-- 1 file changed, 29 insertions(+), 2 deletions(-) diff --git a/drivers/nfc/microread/microread.c b/drivers/nfc/microread/microread.c index 4149c5d735bd..9a7a4fd6796b 100644 --- a/drivers/nfc/microread/microread.c +++ b/drivers/nfc/microread/microread.c @@ -483,13 +483,19 @@ static void microread_target_discovered(struct nfc_hci_dev *hdev, u8 gate, switch (gate) { case MICROREAD_GATE_ID_MREAD_ISO_A: + if (skb->len < MICROREAD_EMCF_A_UID) { + r = -EINVAL; + goto exit_free; + } + targets->supported_protocols = nfc_hci_sak_to_protocol(skb->data[MICROREAD_EMCF_A_SAK]); targets->sens_res = be16_to_cpu(*(u16 *)&skb->data[MICROREAD_EMCF_A_ATQA]); targets->sel_res = skb->data[MICROREAD_EMCF_A_SAK]; targets->nfcid1_len = skb->data[MICROREAD_EMCF_A_LEN]; - if (targets->nfcid1_len > sizeof(targets->nfcid1)) { + if (targets->nfcid1_len > sizeof(targets->nfcid1) || + skb->len - MICROREAD_EMCF_A_UID < targets->nfcid1_len) { r = -EINVAL; goto exit_free; } @@ -497,13 +503,19 @@ static void microread_target_discovered(struct nfc_hci_dev *hdev, u8 gate, targets->nfcid1_len); break; case MICROREAD_GATE_ID_MREAD_ISO_A_3: + if (skb->len < MICROREAD_EMCF_A3_UID) { + r = -EINVAL; + goto exit_free; + } + targets->supported_protocols = nfc_hci_sak_to_protocol(skb->data[MICROREAD_EMCF_A3_SAK]); targets->sens_res = be16_to_cpu(*(u16 *)&skb->data[MICROREAD_EMCF_A3_ATQA]); targets->sel_res = skb->data[MICROREAD_EMCF_A3_SAK]; targets->nfcid1_len = skb->data[MICROREAD_EMCF_A3_LEN]; - if (targets->nfcid1_len > sizeof(targets->nfcid1)) { + if (targets->nfcid1_len > sizeof(targets->nfcid1) || + skb->len - MICROREAD_EMCF_A3_UID < targets->nfcid1_len) { r = -EINVAL; goto exit_free; } @@ -511,11 +523,21 @@ static void microread_target_discovered(struct nfc_hci_dev *hdev, u8 gate, targets->nfcid1_len); break; case MICROREAD_GATE_ID_MREAD_ISO_B: + if (skb->len < MICROREAD_EMCF_B_UID + 4) { + r = -EINVAL; + goto exit_free; + } + targets->supported_protocols = NFC_PROTO_ISO14443_B_MASK; memcpy(targets->nfcid1, &skb->data[MICROREAD_EMCF_B_UID], 4); targets->nfcid1_len = 4; break; case MICROREAD_GATE_ID_MREAD_NFC_T1: + if (skb->len < MICROREAD_EMCF_T1_UID + 4) { + r = -EINVAL; + goto exit_free; + } + targets->supported_protocols = NFC_PROTO_JEWEL_MASK; targets->sens_res = le16_to_cpu(*(u16 *)&skb->data[MICROREAD_EMCF_T1_ATQA]); @@ -523,6 +545,11 @@ static void microread_target_discovered(struct nfc_hci_dev *hdev, u8 gate, targets->nfcid1_len = 4; break; case MICROREAD_GATE_ID_MREAD_NFC_T3: + if (skb->len < MICROREAD_EMCF_T3_UID + 8) { + r = -EINVAL; + goto exit_free; + } + targets->supported_protocols = NFC_PROTO_FELICA_MASK; memcpy(targets->nfcid1, &skb->data[MICROREAD_EMCF_T3_UID], 8); targets->nfcid1_len = 8; -- 2.43.0