{
   "containers": {
      "cna": {
         "providerMetadata": {
            "orgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038"
         },
         "descriptions": [
            {
               "lang": "en",
               "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nuserfaultfd: release page in error path to avoid BUG_ON\n\nConsider the following sequence of events:\n\n1. Userspace issues a UFFD ioctl, which ends up calling into\n   shmem_mfill_atomic_pte(). We successfully account the blocks, we\n   shmem_alloc_page(), but then the copy_from_user() fails. We return\n   -ENOENT. We don't release the page we allocated.\n2. Our caller detects this error code, tries the copy_from_user() after\n   dropping the mmap_lock, and retries, calling back into\n   shmem_mfill_atomic_pte().\n3. Meanwhile, let's say another process filled up the tmpfs being used.\n4. So shmem_mfill_atomic_pte() fails to account blocks this time, and\n   immediately returns - without releasing the page.\n\nThis triggers a BUG_ON in our caller, which asserts that the page\nshould always be consumed, unless -ENOENT is returned.\n\nTo fix this, detect if we have such a \"dangling\" page when accounting\nfails, and if so, release it before returning."
            }
         ],
         "affected": [
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "unaffected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "mm/shmem.c"
               ],
               "versions": [
                  {
                     "version": "cb658a453b93",
                     "lessThan": "319116227e52",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "cb658a453b93",
                     "lessThan": "07c9b834c97d",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "cb658a453b93",
                     "lessThan": "b3f1731c6d7f",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "cb658a453b93",
                     "lessThan": "140cfd998012",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "cb658a453b93",
                     "lessThan": "ad5312797303",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "cb658a453b93",
                     "lessThan": "2d59a0ed8b26",
                     "status": "affected",
                     "versionType": "git"
                  },
                  {
                     "version": "cb658a453b93",
                     "lessThan": "7ed9d238c7db",
                     "status": "affected",
                     "versionType": "git"
                  }
               ]
            },
            {
               "product": "Linux",
               "vendor": "Linux",
               "defaultStatus": "affected",
               "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
               "programFiles": [
                  "mm/shmem.c"
               ],
               "versions": [
                  {
                     "version": "4.11",
                     "status": "affected"
                  },
                  {
                     "version": "0",
                     "lessThan": "4.11",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "4.14.233",
                     "lessThanOrEqual": "4.14.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "4.19.191",
                     "lessThanOrEqual": "4.19.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.4.120",
                     "lessThanOrEqual": "5.4.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.10.38",
                     "lessThanOrEqual": "5.10.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.11.22",
                     "lessThanOrEqual": "5.11.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.12.5",
                     "lessThanOrEqual": "5.12.*",
                     "status": "unaffected",
                     "versionType": "custom"
                  },
                  {
                     "version": "5.13",
                     "lessThanOrEqual": "*",
                     "status": "unaffected",
                     "versionType": "original_commit_for_fix"
                  }
               ]
            }
         ],
         "references": [
            {
               "url": "https://git.kernel.org/stable/c/319116227e52d49eee671f0aa278bac89b3c1b69"
            },
            {
               "url": "https://git.kernel.org/stable/c/07c9b834c97d0fa3402fb7f3f3b32df370a6ff1f"
            },
            {
               "url": "https://git.kernel.org/stable/c/b3f1731c6d7fbc1ebe3ed8eff6d6bec56d76ff43"
            },
            {
               "url": "https://git.kernel.org/stable/c/140cfd9980124aecb6c03ef2e69c72d0548744de"
            },
            {
               "url": "https://git.kernel.org/stable/c/ad53127973034c63b5348715a1043d0e80ceb330"
            },
            {
               "url": "https://git.kernel.org/stable/c/2d59a0ed8b26b8f3638d8afc31f839e27759f1f6"
            },
            {
               "url": "https://git.kernel.org/stable/c/7ed9d238c7dbb1fdb63ad96a6184985151b0171c"
            }
         ],
         "title": "userfaultfd: release page in error path to avoid BUG_ON",
         "x_generator": {
            "engine": "bippy-a5840b7849dd"
         }
      }
   },
   "cveMetadata": {
      "assignerOrgId": "f4215fc3-5b6b-47ff-a258-f7189bd81038",
      "cveID": "CVE-2021-46988",
      "requesterUserId": "gregkh@kernel.org",
      "serial": "1",
      "state": "PUBLISHED"
   },
   "dataType": "CVE_RECORD",
   "dataVersion": "5.0"
}