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Thu, 09 Apr 2026 22:35:14 +0000 (UTC) From: =?UTF-8?q?Lek=C3=AB=20Hap=C3=A7iu?= To: netdev@vger.kernel.org Cc: linux-wireless@vger.kernel.org, stable@vger.kernel.org, krzysztof.kozlowski@linaro.org, =?UTF-8?q?Lek=C3=AB=20Hap=C3=A7iu?= Subject: [PATCH net 4/4] nfc: digital: Fix OOB read of DID byte in digital_tg_recv_dep_req() Date: Fri, 10 Apr 2026 00:34:34 +0200 Message-ID: <20260409223436.1887988-5-snowwlake@icloud.com> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20260409223436.1887988-1-snowwlake@icloud.com> References: <20260409223436.1887988-1-snowwlake@icloud.com> Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Proofpoint-GUID: HdqTIsLjanfCzdreGKM4hW60-mkcGHO3 X-Proofpoint-ORIG-GUID: HdqTIsLjanfCzdreGKM4hW60-mkcGHO3 X-Authority-Info-Out: v=2.4 cv=BZ7VE7t2 c=1 sm=1 tr=0 ts=69d829a4 cx=c_apl:c_pps:t_out a=YrL12D//S6tul8v/L+6tKg==:117 a=YrL12D//S6tul8v/L+6tKg==:17 a=IkcTkHD0fZMA:10 a=A5OVakUREuEA:10 a=M51BFTxLslgA:10 a=x7bEGLp0ZPQA:10 a=LbuW6tbUWPcA:10 a=VkNPw1HP01LnGYTKEx00:22 a=VwQbUJbxAAAA:8 a=v3ZZPjhaAAAA:8 a=_7PiEvq1_GSvmz9hKDsA:9 a=3ZKOabzyN94A:10 a=QEXdDO2ut3YA:10 a=JKcXVnpmuwdQ7RL0mgk_:22 a=5Q-93EyGrU3sW_9myDOF:22 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjYwNDA5MDIwOSBTYWx0ZWRfX4iUYDphLCofg 3jOpr/sy0Kyu78wIHHnO5jRq2385LdxloMaBz1uh4T9hwBWqiBDsFt1DKnnHAJuxt5uzFy2T5EH YCZlEGUcPqsrGsYdqcVT9goRJxJjN00LyCut5Zo3pf8OZdpk2JJSqkz1ZzFQLf+wPtwTndclfG2 PJrJrXITmZmTJDBvIGg7PeGT7W8ZmTlJ8K2xg3YFdtUVu5VO6rscLQX0K+UJ8ESuzrRaH+BDQVY A+vsibnsze21LEG6JU45CKkKWcfcXDNOllVEVTaVDsiVJuXOVyFboSxPF8UnDGrUNZx0kG9HzhL Y3VUb/yC6kQLVE8tvB/IMkHw/655Gq3mrni48Z+Lv2N04mJJZK5TPn+kKQpgo8= X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1143,Hydra:6.1.51,FMLib:17.12.100.49 definitions=2026-04-09_04,2026-04-09_02,2025-10-01_01 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 malwarescore=0 phishscore=0 spamscore=0 suspectscore=0 mlxscore=0 adultscore=0 clxscore=1015 mlxlogscore=999 bulkscore=0 lowpriorityscore=0 classifier=spam authscore=0 adjust=0 reason=mlx scancount=1 engine=8.22.0-2601150000 definitions=main-2604090209 digital_tg_recv_dep_req() guards against short frames with: if (resp->len < size ...) /* size = sizeof(struct digital_dep_req_res) = 3 */ This guarantees resp->len >= 3 (dir + cmd + pfb). However, when the DID bit is set in pfb, the code immediately accesses resp->data[3] — the DID byte — which is one byte past the guaranteed minimum: if (DIGITAL_NFC_DEP_DID_BIT_SET(pfb)) { if (ddev->did && (ddev->did == resp->data[3])) { A remote NFC-DEP initiator can trigger this with a 3-byte DEP_REQ frame that has the DID bit set in the PFB field, causing a 1-byte out-of-bounds read of kernel heap memory. Increment the minimum required length to 4 when the DID bit is present before accessing resp->data[3], mirroring the pattern used for the size++ / check at the end of the DID block. Fixes: 7d0911c07b44 ("NFC Digital: Implement NFC-DEP target TX and RX") Cc: stable@vger.kernel.org Signed-off-by: Lekë Hapçiu --- net/nfc/digital_dep.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/net/nfc/digital_dep.c b/net/nfc/digital_dep.c index XXXXXXX..XXXXXXX 100644 --- a/net/nfc/digital_dep.c +++ b/net/nfc/digital_dep.c @@ -1117,6 +1117,11 @@ static int digital_tg_recv_dep_req(struct nfc_digital_dev *ddev, void *arg, pfb = dep_req->pfb; if (DIGITAL_NFC_DEP_DID_BIT_SET(pfb)) { + if (resp->len < size + 1) { + rc = -EIO; + goto exit; + } + if (ddev->did && (ddev->did == resp->data[3])) { size++; } else { -- 2.34.1