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[69.172.89.235]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b2d4f3afebsm108369605ad.72.2026.04.13.02.02.11 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Mon, 13 Apr 2026 02:02:12 -0700 (PDT) From: Dudu Lu To: netdev@vger.kernel.org Cc: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, Dudu Lu Subject: [PATCH] nfc: llcp: Fix TLV parsing off-by-one in LLCP connect and SNL Date: Mon, 13 Apr 2026 17:02:08 +0800 Message-Id: <20260413090208.78649-1-phx0fer@gmail.com> X-Mailer: git-send-email 2.39.3 (Apple Git-145) Precedence: bulk X-Mailing-List: netdev@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit The TLV parsing loops in nfc_llcp_connect_sn() and nfc_llcp_recv_snl() check `offset < tlv_array_len` before accessing both tlv[0] (type) and tlv[1] (length). When exactly one byte remains (offset == tlv_array_len - 1), the access to tlv[1] reads one byte beyond the skb data buffer. Fix both sites by changing the loop condition to `offset + 1 < tlv_array_len`, ensuring at least 2 bytes are available before reading the type and length fields. Signed-off-by: Dudu Lu --- net/nfc/llcp_core.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/net/nfc/llcp_core.c b/net/nfc/llcp_core.c index 366d7566308c..d1a75b9445e1 100644 --- a/net/nfc/llcp_core.c +++ b/net/nfc/llcp_core.c @@ -852,7 +852,7 @@ static const u8 *nfc_llcp_connect_sn(const struct sk_buff *skb, size_t *sn_len) const u8 *tlv = &skb->data[2]; size_t tlv_array_len = skb->len - LLCP_HEADER_SIZE, offset = 0; - while (offset < tlv_array_len) { + while (offset + 1 < tlv_array_len) { type = tlv[0]; length = tlv[1]; @@ -1297,7 +1297,7 @@ static void nfc_llcp_recv_snl(struct nfc_llcp_local *local, offset = 0; sdres_tlvs_len = 0; - while (offset < tlv_len) { + while (offset + 1 < tlv_len) { type = tlv[0]; length = tlv[1]; -- 2.39.3 (Apple Git-145)