linux-kernel - [PATCH net-next v2] nfc: llcp: fix possible use of uninitialized variable in nfc_llcp_send

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Message-Id: <20230513115204.179437-1-krzysztof.kozlowski@linaro.org>
Date:   Sat, 13 May 2023 13:52:04 +0200
From:   Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To:     Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>,
        "David S. Miller" <davem@...emloft.net>,
        Eric Dumazet <edumazet@...gle.com>,
        Jakub Kicinski <kuba@...nel.org>,
        Paolo Abeni <pabeni@...hat.com>,
        Thierry Escande <thierry.escande@...labora.com>,
        Samuel Ortiz <sameo@...ux.intel.com>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH net-next v2] nfc: llcp: fix possible use of uninitialized variable in nfc_llcp_send_connect()

If sock->service_name is NULL, the local variable
service_name_tlv_length will not be assigned by nfc_llcp_build_tlv(),
later leading to using value frmo the stack.  Smatch warning:

  net/nfc/llcp_commands.c:442 nfc_llcp_send_connect() error: uninitialized symbol 'service_name_tlv_length'.

Fixes: de9e5aeb4f40 ("NFC: llcp: Fix usage of llcp_add_tlv()")
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>

---

Changes in v2:
1. Fix typo in subject prefix.
---
 net/nfc/llcp_commands.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/nfc/llcp_commands.c b/net/nfc/llcp_commands.c
index 41e3a20c8935..cdb001de0692 100644
--- a/net/nfc/llcp_commands.c
+++ b/net/nfc/llcp_commands.c
@@ -390,7 +390,8 @@ int nfc_llcp_send_connect(struct nfc_llcp_sock *sock)
 	const u8 *service_name_tlv = NULL;
 	const u8 *miux_tlv = NULL;
 	const u8 *rw_tlv = NULL;
-	u8 service_name_tlv_length, miux_tlv_length,  rw_tlv_length, rw;
+	u8 service_name_tlv_length = 0;
+	u8 miux_tlv_length,  rw_tlv_length, rw;
 	int err;
 	u16 size = 0;
 	__be16 miux;
-- 
2.34.1