ip6_vti: set netns_immutable on the fallback device.

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/ipv6/ip6_vti.c"
                    ],
                    "versions": [
                        {
                            "version": "61220ab349485d911083d0b7990ccd3db6c63297",
                            "lessThan": "12acc977838c943636fb01e2f3087d2e4cc3b7cc",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "61220ab349485d911083d0b7990ccd3db6c63297",
                            "lessThan": "7f28e3948c59481f8db9c9638e204258d26b4e41",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "61220ab349485d911083d0b7990ccd3db6c63297",
                            "lessThan": "12c65e2c7fef507551bd7b52123598a761662c01",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "61220ab349485d911083d0b7990ccd3db6c63297",
                            "lessThan": "f4b6b4af7ef0661ac153c6f7eb1030aa8482c1a3",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "61220ab349485d911083d0b7990ccd3db6c63297",
                            "lessThan": "c5dbd669db5a426b3025512322e1bf2cdbe14305",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "61220ab349485d911083d0b7990ccd3db6c63297",
                            "lessThan": "ecf8904067dcba0dad86ece80874841e60317885",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "61220ab349485d911083d0b7990ccd3db6c63297",
                            "lessThan": "dcdce3bc9f08026ff3739ee7339e1bef526fc5f3",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "61220ab349485d911083d0b7990ccd3db6c63297",
                            "lessThan": "d289d5307762d1838aaece22c6b6fcad9e8865f9",
                            "status": "affected",
                            "versionType": "git"
                        }
                    ]
                }

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/ipv6/ip6_vti.c"
                    ],
                    "versions": [
                        {
                            "version": "3.15",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "3.15",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.10.260",
                            "lessThanOrEqual": "5.10.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "5.15.211",
                            "lessThanOrEqual": "5.15.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.1.177",
                            "lessThanOrEqual": "6.1.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.144",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.95",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.36",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.0.13",
                            "lessThanOrEqual": "7.0.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.1",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }