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Wed, 09 Sep 2026 05:14:51 -0700 (PDT) From: =?UTF-8?q?=C3=96mer=20Mete=20Kaya?= To: oe-linux-nfc@lists.linux.dev Cc: david@ixit.cz, horms@kernel.org, linux-kernel@vger.kernel.org, =?UTF-8?q?=C3=96mer=20Mete=20Kaya?= Subject: [PATCH net] nfc: llcp: fix WKS SAP hijacking via prefix match in nfc_llcp_wks_sap() Date: Wed, 9 Sep 2026 15:14:31 +0300 Message-ID: <20260909121437.33744-1-omermetekaya0@gmail.com> X-Mailer: git-send-email 2.55.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit nfc_llcp_wks_sap() compares only service_name_len bytes, so a short service_name like "u" matches longer WKS strings like "urn:nfc:sn:snep". Fix by requiring exact length match before strncmp(). Fixes: d646960f7986 ("NFC: Initial LLCP support") Signed-off-by: Ömer Mete Kaya --- net/nfc/llcp_core.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/net/nfc/llcp_core.c b/net/nfc/llcp_core.c index fda236e4d9fd..5025d8bdfc36 100644 --- a/net/nfc/llcp_core.c +++ b/net/nfc/llcp_core.c @@ -352,7 +352,8 @@ static int nfc_llcp_wks_sap(const char *service_name, size_t service_name_len) if (wks[sap] == NULL) continue; - if (strncmp(wks[sap], service_name, service_name_len) == 0) + if (strlen(wks[sap]) == service_name_len && + !strncmp(wks[sap], service_name, service_name_len)) return sap; } -- 2.55.0