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From:   Arnd Bergmann <arnd@kernel.org>
To:     Edward Cree <ecree.xilinx@gmail.com>,
        Martin Habets <habetsm.xilinx@gmail.com>,
        Jakub Kicinski <kuba@kernel.org>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Paolo Abeni <pabeni@redhat.com>,
        Simon Horman <simon.horman@corigine.com>,
        Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>,
        netdev@vger.kernel.org, linux-net-drivers@amd.com,
        linux-kernel@vger.kernel.org
Subject: [PATCH 1/2] sfc: fix uninitialized variable use
Date:   Fri, 16 Jun 2023 11:08:18 +0200
Message-Id: <20230616090844.2677815-1-arnd@kernel.org>
MIME-Version: 1.0
Content-Transfer-Encoding: 8bit
Precedence: bulk

From: Arnd Bergmann <arnd@arndb.de>

The new efx_bind_neigh() function contains a broken code path when IPV6 is
disabled:

drivers/net/ethernet/sfc/tc_encap_actions.c:144:7: error: variable 'n' is used uninitialized whenever 'if' condition is true [-Werror,-Wsometimes-uninitialized]
                if (encap->type & EFX_ENCAP_FLAG_IPV6) {
                    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc_encap_actions.c:184:8: note: uninitialized use occurs here
                if (!n) {
                     ^
drivers/net/ethernet/sfc/tc_encap_actions.c:144:3: note: remove the 'if' if its condition is always false
                if (encap->type & EFX_ENCAP_FLAG_IPV6) {
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
drivers/net/ethernet/sfc/tc_encap_actions.c:141:22: note: initialize the variable 'n' to silence this warning
                struct neighbour *n;
                                   ^
                                    = NULL

Change it to use the existing error handling path here.

Fixes: 7e5e7d800011a ("sfc: neighbour lookup for TC encap action offload")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
 drivers/net/ethernet/sfc/tc_encap_actions.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/net/ethernet/sfc/tc_encap_actions.c b/drivers/net/ethernet/sfc/tc_encap_actions.c
index aac259528e73e..cfd76d5bbdd48 100644
--- a/drivers/net/ethernet/sfc/tc_encap_actions.c
+++ b/drivers/net/ethernet/sfc/tc_encap_actions.c
@@ -163,6 +163,7 @@ static int efx_bind_neigh(struct efx_nic *efx,
 			 * enabled how did someone create an IPv6 tunnel_key?
 			 */
 			rc = -EOPNOTSUPP;
+			n = NULL;
 			NL_SET_ERR_MSG_MOD(extack, "No IPv6 support (neigh bind)");
 #endif
 		} else {
-- 
2.39.2