ipv6: fix panic when forwarding a pkt with no in6 dev

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/ipv6/ip6_output.c"
                    ],
                    "versions": [
                        {
                            "version": "bff0854e2f804f68d3e93d19e4580dbd69777e1d",
                            "lessThan": "74b68f5249f16c5f7f675d0f604fa6ae20e3a151",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "7f4848229e91d508102b30396b8a1b710ac23637",
                            "lessThan": "ab2f5afb7af5c68389e8c7dd29e0a98fbeaaa435",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "79ec7b5b2f4fe38e5c7459ed0bdff4ef3386ab63",
                            "lessThan": "a263712ba8c9ded25dd9d2d5ced11bcea5b33a3e",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "ccd27f05ae7b8ebc40af5b004e94517a919aa862",
                            "lessThan": "adee01bbf6cb5b3e4ed08be8ff866aac90f13836",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "ccd27f05ae7b8ebc40af5b004e94517a919aa862",
                            "lessThan": "e69fb3de87a8923e5931a272a38fa3cceb01da44",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "ccd27f05ae7b8ebc40af5b004e94517a919aa862",
                            "lessThan": "e3fa461d8b0e185b7da8a101fe94dfe6dd500ac0",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "350e10d217337480158b604bbf6601c50ed161c6",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "4.19.199",
                            "lessThan": "4.19.239",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.4.136",
                            "lessThan": "5.4.190",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.10.54",
                            "lessThan": "5.10.112",
                            "status": "affected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.13.6",
                            "lessThan": "5.14",
                            "status": "affected",
                            "versionType": "semver"
                        }
                    ]
                }

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/ipv6/ip6_output.c"
                    ],
                    "versions": [
                        {
                            "version": "5.14",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "5.14",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "4.19.239",
                            "lessThanOrEqual": "4.19.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.4.190",
                            "lessThanOrEqual": "5.4.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.10.112",
                            "lessThanOrEqual": "5.10.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.15.35",
                            "lessThanOrEqual": "5.15.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.17.4",
                            "lessThanOrEqual": "5.17.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.18",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }