CVE-2021-47420 drm/amdkfd: fix a potential ttm->sg memory leak

[
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "unaffected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c"
    ],
    "versions": [
      {
        "version": "264fb4d332f5e76743818480e482464437837c52",
        "lessThan": "7e5ce6029b627efb4a004746cfdc1eeff850e6eb",
        "status": "affected",
        "versionType": "git"
      },
      {
        "version": "264fb4d332f5e76743818480e482464437837c52",
        "lessThan": "b072ef1215aca33186e3a10109e872e528a9e516",
        "status": "affected",
        "versionType": "git"
      }
    ]
  },
  {
    "product": "Linux",
    "vendor": "Linux",
    "defaultStatus": "affected",
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "programFiles": [
      "drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c"
    ],
    "versions": [
      {
        "version": "5.14",
        "status": "affected"
      },
      {
        "version": "0",
        "lessThan": "5.14",
        "status": "unaffected",
        "versionType": "semver"
      },
      {
        "version": "5.14.12",
        "lessThanOrEqual": "5.14.*",
        "status": "unaffected",
        "versionType": "semver"
      },
      {
        "version": "5.15",
        "lessThanOrEqual": "*",
        "status": "unaffected",
        "versionType": "original_commit_for_fix"
      }
    ]
  }
]