net/smc: do not dereference an unset send buffer on the SMC-D teardown path

{
                    "product": "Linux",
                    "vendor": "Linux",
                    "defaultStatus": "unaffected",
                    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
                    "programFiles": [
                        "net/smc/af_smc.c",
                        "net/smc/smc_tx.h"
                    ],
                    "versions": [
                        {
                            "version": "21f6f41e82e59740e26e06e77bdf58dc7f6f08dd",
                            "lessThan": "ab26e12dd5d2f43d939fcf456933a816e81d2e51",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "ae2be35cbed2c8385e890147ea321a3fcc3ca5fa",
                            "lessThan": "e3fcff8d22a6c9540748846cd800443a643553a6",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "ae2be35cbed2c8385e890147ea321a3fcc3ca5fa",
                            "lessThan": "f950e1b1f0aad334f9a9ee552c4dd5b794ebdd45",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "ae2be35cbed2c8385e890147ea321a3fcc3ca5fa",
                            "lessThan": "f517cf02033801a28f98d86ca613a3533cf066b3",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "ae2be35cbed2c8385e890147ea321a3fcc3ca5fa",
                            "lessThan": "b395dd319cea422239cb45b998fb38d7e373af87",
                            "status": "affected",
                            "versionType": "git"
                        },
                        {
                            "version": "6.6.66",
                            "lessThan": "6.6.157",
                            "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/smc/af_smc.c",
                        "net/smc/smc_tx.h"
                    ],
                    "versions": [
                        {
                            "version": "6.10",
                            "status": "affected"
                        },
                        {
                            "version": "0",
                            "lessThan": "6.10",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.6.157",
                            "lessThanOrEqual": "6.6.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.12.109",
                            "lessThanOrEqual": "6.12.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "6.18.50",
                            "lessThanOrEqual": "6.18.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.2.4",
                            "lessThanOrEqual": "7.2.*",
                            "status": "unaffected",
                            "versionType": "semver"
                        },
                        {
                            "version": "7.3",
                            "lessThanOrEqual": "*",
                            "status": "unaffected",
                            "versionType": "original_commit_for_fix"
                        }
                    ]
                }