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From:   Arnd Bergmann <arnd@kernel.org>
To:     Edward Cree <ecree.xilinx@gmail.com>,
        Martin Habets <habetsm.xilinx@gmail.com>,
        "David S. Miller" <davem@davemloft.net>,
        Eric Dumazet <edumazet@google.com>,
        Jakub Kicinski <kuba@kernel.org>,
        Paolo Abeni <pabeni@redhat.com>,
        Pieter Jansen van Vuuren <pieter.jansen-van-vuuren@amd.com>,
        Simon Horman <simon.horman@corigine.com>
Cc:     Arnd Bergmann <arnd@arndb.de>, netdev@vger.kernel.org,
        linux-net-drivers@amd.com, linux-kernel@vger.kernel.org
Subject: [PATCH 2/3] [v2] sfc: fix uninitialized variable use
Date:   Mon, 19 Jun 2023 11:12:10 +0200
Message-Id: <20230619091215.2731541-2-arnd@kernel.org>
In-Reply-To: <20230619091215.2731541-1-arnd@kernel.org>
References: <20230619091215.2731541-1-arnd@kernel.org>
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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")
Suggested-by: Edward Cree <ecree.xilinx@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
---
v2: use 'goto' instead of incorrectly entering another error path
---
 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..7e8bcdb222ad1 100644
--- a/drivers/net/ethernet/sfc/tc_encap_actions.c
+++ b/drivers/net/ethernet/sfc/tc_encap_actions.c
@@ -164,6 +164,7 @@ static int efx_bind_neigh(struct efx_nic *efx,
 			 */
 			rc = -EOPNOTSUPP;
 			NL_SET_ERR_MSG_MOD(extack, "No IPv6 support (neigh bind)");
+			goto out_free;
 #endif
 		} else {
 			rt = ip_route_output_key(net, &flow4);
-- 
2.39.2