ipv6: mcast: use copy-on-write RCU updates in ip6_mc_source()

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "include/net/if_inet6.h",
                        "net/ipv6/mcast.c"
                    ],
                    "versions": [
                        {
                            "version": "882ba1f73c06831f2a21044ebd8864c485ac04f2",
                            "lessThan": "ac51321d3b2391860a935820ebcf4d8b9bb16a8a",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "882ba1f73c06831f2a21044ebd8864c485ac04f2",
                            "lessThan": "dba00514bf668c26cb4900e9f0da84bf96bf065a",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "882ba1f73c06831f2a21044ebd8864c485ac04f2",
                            "lessThan": "2c2091e2ee93049fc513ad1e6c99d8b6c809f467",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "882ba1f73c06831f2a21044ebd8864c485ac04f2",
                            "lessThan": "20db91a052332ef5552bd2f651ffb9db911cf67b",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "882ba1f73c06831f2a21044ebd8864c485ac04f2",
                            "lessThan": "c073d1b070f171d206b19c98d71739a97f15b3f1",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "47c75e3923c8d562fea8daf0ccf31546a7bef0ea",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "5.10.261",
                            "lessThan": "5.11",
                            "status": "affected",
                            "versionType": "semver"
                        }
                    ]
                }

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "affected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "include/net/if_inet6.h",
                        "net/ipv6/mcast.c"
                    ],
                    "versions": [
                        {
                            "version": "5.13",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "5.13",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.158",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.112",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.53",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2.7",
                            "lessThanOrEqual": "7.2.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.3",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }