{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-98044",
  "modified": "2026-10-07T14:35:31Z",
  "upstream": [
    "CVE-2026-98044"
  ],
  "published": "2026-09-25T10:24:31Z",
  "summary": "bpf: Reject legacy packet loads from callbacks",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Reject legacy packet loads from callbacks\n\ncheck_ld_abs() models a failed BPF_LD_ABS or BPF_LD_IND in a\nsubprogram as an implicit return with R0 set to zero. It calls\nprepare_func_exit() to explore this synthesized path.\n\nWhen the load is reached directly from a synchronous callback,\nprepare_func_exit() enforces the callback return contract and marks R0\nprecise. R0 is not derived from a real instruction on this path, so\nprecision backtracking reaches the callback call with R0 still requested\nand triggers the \"callback unexpected regs\" verifier bug. A privileged\nprogram loader can therefore cause a verifier warning and an -EFAULT\nBPF_PROG_LOAD.\n\nThese legacy packet-load instructions are deprecated. Reject them from\ncallbacks rather than complicating their implicit-return model. Check all\nactive frames before constructing the implicit return so nested static\nsubprograms cannot hide the callback context.\n\nGlobal functions are verified independently with a fresh frame zero, so\nan active-frame check cannot identify a global function called from a\ncallback. Also check the complete subprogram call graph during stack-depth\nvalidation and reject a function containing a legacy load when any caller\nis a callback. This covers global and static descendants without making\nhas_ld_abs transitive, preserving its per-function BTF return-type check.\nOrdinary uses outside callbacks remain supported.",
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.12.109-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.12.109+rpt-rpi-2712",
            "binary_version": "1:6.12.109-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.109+rpt-rpi-v6",
            "binary_version": "1:6.12.109-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.109+rpt-rpi-v7",
            "binary_version": "1:6.12.109-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.109+rpt-rpi-v7l",
            "binary_version": "1:6.12.109-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.109+rpt-rpi-v8",
            "binary_version": "1:6.12.109-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.12.109+rpt-rpi-v8-rt",
            "binary_version": "1:6.12.109-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.12.109-1+rpt1": {
            "linux_commit": "7d1826930811232688a50c99c540fbb137aed081",
            "upstream_version": "6.12.109",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": null
          }
        }
      }
    },
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:13",
        "name": "linux"
      },
      "versions": [
        "1:6.18.50-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-2712",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v6",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v7",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v8",
            "binary_version": "1:6.18.50-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.18.50+rpt-rpi-v8-rt",
            "binary_version": "1:6.18.50-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.18.50-1+rpt1": {
            "linux_commit": "cff533aec2fa601846766b32ff57204e0a61bed7",
            "upstream_version": "6.18.50",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.18.53"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-98044"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/3484a99303912db62428494a9061212049027e57"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/bc489c0c9b8c86bd7fac42cfd1bb152f042fca56"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/e7d28823c662128caae63f14e16bd394916c139b"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-09-25T10:24:31Z"
  }
}