{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-23243",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-23243"
  ],
  "published": "2026-03-18T10:05:24Z",
  "summary": "RDMA/umad: Reject negative data_len in ib_umad_write",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nRDMA/umad: Reject negative data_len in ib_umad_write\n\nib_umad_write computes data_len from user-controlled count and the\nMAD header sizes. With a mismatched user MAD header size and RMPP\nheader length, data_len can become negative and reach ib_create_send_mad().\nThis can make the padding calculation exceed the segment size and trigger\nan out-of-bounds memset in alloc_send_rmpp_list().\n\nAdd an explicit check to reject negative data_len before creating the\nsend buffer.\n\nKASAN splat:\n[  211.363464] BUG: KASAN: slab-out-of-bounds in ib_create_send_mad+0xa01/0x11b0\n[  211.364077] Write of size 220 at addr ffff88800c3fa1f8 by task spray_thread/102\n[  211.365867] ib_create_send_mad+0xa01/0x11b0\n[  211.365887] ib_umad_write+0x853/0x1c80",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.165",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-23243"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/1371ef6b1ecf3676b8942f5dfb3634fb0648128e"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/362e45fd9069ffa1523f9f1633b606ebf72060d7"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6eb2919474ca105c5b13d19574e25f0ddcf19ca2"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/a6a3e4af10993cb9e4b8f0548680aba0ab5f3b0d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/9c80d688f402539dfc8f336de1380d6b4ee14316"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/205955f29c26330b1dc7fdeadd5bb97c38e26f56"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/52ab82cc5cf8ada5c3fb6ffe8f32fdb2fc27a34b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/5551b02fdbfd85a325bb857f3a8f9c9f33397ed2"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The vulnerability is in ib_umad_write(), the write handler for /dev/infiniband/umadX character device files, requiring local system access to open and write to the device.\nAC:L - The attacker reliably controls the count parameter passed to write() and can craft input to make data_len negative, triggering the OOB write deterministically with no race or special conditions.\nPR:L - The /dev/infiniband/umadX device has no capability checks in the code path. On RDMA-enabled systems (HPC clusters, cloud servers), udev rules commonly grant access to unprivileged users. An ioctl to register a MAD agent is needed first but requires no special privileges.\nUI:N - No user interaction is required. The attacker directly opens the device file, registers a MAD agent via ioctl, and triggers the bug by writing crafted data.\nS:U - The vulnerability operates within kernel space and does not cross a security boundary such as a VM or sandbox escape.\nC:H - The out-of-bounds memset write into slab memory can corrupt adjacent heap objects. In a controlled exploit, this memory corruption can be leveraged via heap spraying to gain arbitrary read primitives.\nI:H - KASAN confirmed a slab out-of-bounds write of 220 bytes. This heap corruption can be exploited to overwrite adjacent slab objects, enabling arbitrary write primitives and potential code execution.\nA:H - The out-of-bounds write corrupts slab memory, causing kernel crashes as confirmed by the KASAN splat. This is a reliable kernel panic/oops."
    }
  }
}