arm64: entry: avoid kprobe recursion

{
  "id": "4bc74dfdce2ebdf1b5f2d4f8382d9870bc0e6cf825efc71040c1ff9e6157c044",
  "url": "https://osv.dev/vulnerability/CVE-2022-49888",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "arm64: entry: avoid kprobe recursion",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: arm64: entry: avoid kprobe recursion The cortex_a76_erratum_1463225_debug_handler() function is called when handling debug exceptions (and synchronous exceptions from BRK instructions), and so is called when a probed function executes. If the compiler does not inline cortex_a76_erratum_1463225_debug_handler(), it can be probed. If cortex_a76_erratum_1463225_debug_handler() is probed, any debug exception or software breakpoint exception will result in recursive exceptions leading to a stack overflow. This can be triggered with the ftrace multiple_probes selftest, and as per the example splat below. This is a regression caused by commit: 6459b8469753e9fe (\"arm64: entry: consolidate Cortex-A76 erratum 1463225 workaround\") ... which removed the NOKPROBE_SYMBOL() annotation associated with the function. My intent was that cortex_a76_erratum_1463225_debug_handler() would be inlined into its caller, el1_dbg(), which is marked noinstr and cannot be probed. Mark cortex_a76_erratum_1463225_debug_handler() as __always_inline to ensure this. Example splat prior to this patch (with recursive entries elided): | # echo p cortex_a76_erratum_1463225_debug_handler > /sys/kernel/debug/tracing/kprobe_events | # echo p do_el0_svc >> /sys/kernel/debug/tracing/kprobe_events | # echo 1 > /sys/kernel/debug/tracing/events/kprobes/enable | Insufficient stack space to handle exception! | ESR: 0x0000000096000047 -- DABT (current EL) | FA",
    "evidence": "osv:CVE-2022-49888",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
          {
            "value": "5.15.78",
            "evidence": "/affected/1/ranges"
          },
          {
            "value": "6.0.8",
            "evidence": "/affected/1/ranges"
          }
        ],
        "affected_versions": []
      }
    ],
    "severity": "unknown",
    "structured": {
      "id": "CVE-2022-49888",
      "aliases": [
        "CVE-2022-49888"
      ],
      "affected": [
        {
          "ranges": [
            {
              "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
              "type": "GIT",
              "events": [
                {
                  "introduced": "6459b8469753e9feaa8b34691d097cffad905931"
                },
                {
                  "fixed": "71d6c33fe223255f4416a01514da2c0bc3e283e7"
                },
                {
                  "fixed": "db66629d43b2d12cb43b004a4ca6be1d03228e97"
                },
                {
                  "fixed": "024f4b2e1f874934943eb2d3d288ebc52c79f55c"
                }
              ]
            }
          ],
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49888.json"
          }
        },
        {
          "ranges": [
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.12.0"
                },
                {
                  "fixed": "5.15.78"
                }
              ]
            },
            {
              "type": "ECOSYSTEM",
              "events": [
                {
                  "introduced": "5.16.0"
                },
                {
                  "fixed": "6.0.8"
                }
              ]
            }
          ],
          "package": {
            "name": "Kernel",
            "ecosystem": "Linux"
          },
          "database_specific": {
            "source": "https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2022-49888.json"
          }
        }
      ],
      "modified": "2026-10-28T02:30:32.607909652Z",
      "provider": "osv",
      "references": [
        "https://git.kernel.org/stable/c/024f4b2e1f874934943eb2d3d288ebc52c79f55c",
        "https://git.kernel.org/stable/c/71d6c33fe223255f4416a01514da2c0bc3e283e7",
        "https://git.kernel.org/stable/c/db66629d43b2d12cb43b004a4ca6be1d03228e97",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2022/49xxx/CVE-2022-49888.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2022-49888",
        "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-2022-49888.json"
      }
    },
    "related_cves": [
      {
        "value": "CVE-2022-49888",
        "evidence": "/id"
      }
    ],
    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 499310,
  "published_at": "2025-05-01T14:10:33.183+00:00"
}