arm64: compat: Do not treat syscall number as ESR_ELx for a bad syscall

{
  "id": "55c8bdcc51955f0a993eb3d967a57ddc3f5ffc91b29e2421b6b12004cb2cbebc",
  "url": "https://osv.dev/vulnerability/CVE-2022-49520",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "arm64: compat: Do not treat syscall number as ESR_ELx for a bad syscall",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: arm64: compat: Do not treat syscall number as ESR_ELx for a bad syscall If a compat process tries to execute an unknown system call above the __ARM_NR_COMPAT_END number, the kernel sends a SIGILL signal to the offending process. Information about the error is printed to dmesg in compat_arm_syscall() -> arm64_notify_die() -> arm64_force_sig_fault() -> arm64_show_signal(). arm64_show_signal() interprets a non-zero value for current->thread.fault_code as an exception syndrome and displays the message associated with the ESR_ELx.EC field (bits 31:26). current->thread.fault_code is set in compat_arm_syscall() -> arm64_notify_die() with the bad syscall number instead of a valid ESR_ELx value. This means that the ESR_ELx.EC field has the value that the user set for the syscall number and the kernel can end up printing bogus exception messages*. For example, for the syscall number 0x68000000, which evaluates to ESR_ELx.EC value of 0x1A (ESR_ELx_EC_FPAC) the kernel prints this error: [ 18.349161] syscall[300]: unhandled exception: ERET/ERETAA/ERETAB, ESR 0x68000000, Oops - bad compat syscall(2) in syscall[10000+50000] [ 18.350639] CPU: 2 PID: 300 Comm: syscall Not tainted 5.18.0-rc1 #79 [ 18.351249] Hardware name: Pine64 RockPro64 v2.0 (DT) [..] which is misleading, as the bad compat syscall has nothing to do with pointer authentication. Stop arm64_show_signal() from printing exception syndrome information by having c",
    "evidence": "osv:CVE-2022-49520",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.4.198",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.10.121",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.15.46",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.17.14",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "5.18.3",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2022-49520",
      "aliases": [
        "CVE-2022-49520"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "532826f3712b607256eb30f92f23d1c604d3fa34"
                },
                {
                  "fixed": "efd183d988b416fcdf6f7c298a17ced4859ca77d"
                },
                {
                  "fixed": "ad97425d23af3c3b8d4f6a2bb666cb485087c007"
                },
                {
                  "fixed": "621916afe8cd4f322eb12759b64a2f938d4e551d"
                },
                {
                  "fixed": "095e975f8150ccd7f852eb578c1cdbdd2f517c7a"
                },
                {
                  "fixed": "3910ae71cb963fa2b68e684489d4fc3d105afda0"
                },
                {
                  "fixed": "3fed9e551417b84038b15117732ea4505eee386b"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49520.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "4.17.0"
                },
                {
                  "fixed": "5.4.198"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.5.0"
                },
                {
                  "fixed": "5.10.121"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.11.0"
                },
                {
                  "fixed": "5.15.46"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "5.17.14"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.18.0"
                },
                {
                  "fixed": "5.18.3"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49520.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:42.348607823Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/095e975f8150ccd7f852eb578c1cdbdd2f517c7a",
        "https://git.kernel.org/stable/c/3910ae71cb963fa2b68e684489d4fc3d105afda0",
        "https://git.kernel.org/stable/c/3fed9e551417b84038b15117732ea4505eee386b",
        "https://git.kernel.org/stable/c/621916afe8cd4f322eb12759b64a2f938d4e551d",
        "https://git.kernel.org/stable/c/ad97425d23af3c3b8d4f6a2bb666cb485087c007",
        "https://git.kernel.org/stable/c/efd183d988b416fcdf6f7c298a17ced4859ca77d",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49520.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2022-49520",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49520.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2022-49520",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 509737,
  "published_at": "2025-02-26T02:13:46.336+00:00"
}