{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2024-26689",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2024-26689"
  ],
  "published": "2024-04-03T14:55:57Z",
  "summary": "ceph: prevent use-after-free in encode_cap_msg()",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nceph: prevent use-after-free in encode_cap_msg()\n\nIn fs/ceph/caps.c, in encode_cap_msg(), \"use after free\" error was\ncaught by KASAN at this line - 'ceph_buffer_get(arg->xattr_buf);'. This\nimplies before the refcount could be increment here, it was freed.\n\nIn same file, in \"handle_cap_grant()\" refcount is decremented by this\nline - 'ceph_buffer_put(ci->i_xattrs.blob);'. It appears that a race\noccurred and resource was freed by the latter line before the former\nline could increment it.\n\nencode_cap_msg() is called by __send_cap() and __send_cap() is called by\nceph_check_caps() after calling __prep_cap(). __prep_cap() is where\narg->xattr_buf is assigned to ci->i_xattrs.blob. This is the spot where\nthe refcount must be increased to prevent \"use after free\" error.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.21-1+rpt1",
        "1:6.1.47-1+rpt2",
        "1:6.1.47-1+rpt4",
        "1:6.1.54-1+rpt2",
        "1:6.1.58-1+rpt2",
        "1:6.1.63-1+rpt1",
        "1:6.1.73-1+rpt1"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v6",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v7",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v7l",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi1-rpi-v8",
            "binary_version": "1:6.1.21-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi2-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi2-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi2-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi2-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt2"
          },
          {
            "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"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi4-rpi-2712",
            "binary_version": "1:6.1.54-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi4-rpi-v6",
            "binary_version": "1:6.1.54-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi4-rpi-v7",
            "binary_version": "1:6.1.54-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi4-rpi-v7l",
            "binary_version": "1:6.1.54-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi4-rpi-v8",
            "binary_version": "1:6.1.54-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi6-rpi-2712",
            "binary_version": "1:6.1.58-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi6-rpi-v6",
            "binary_version": "1:6.1.58-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi6-rpi-v7",
            "binary_version": "1:6.1.58-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi6-rpi-v7l",
            "binary_version": "1:6.1.58-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi6-rpi-v8",
            "binary_version": "1:6.1.58-1+rpt2"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi7-rpi-2712",
            "binary_version": "1:6.1.63-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi7-rpi-v6",
            "binary_version": "1:6.1.63-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi7-rpi-v7",
            "binary_version": "1:6.1.63-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi7-rpi-v7l",
            "binary_version": "1:6.1.63-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi7-rpi-v8",
            "binary_version": "1:6.1.63-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi8-rpi-2712",
            "binary_version": "1:6.1.73-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi8-rpi-v6",
            "binary_version": "1:6.1.73-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi8-rpi-v7",
            "binary_version": "1:6.1.73-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi8-rpi-v7l",
            "binary_version": "1:6.1.73-1+rpt1"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi8-rpi-v8",
            "binary_version": "1:6.1.73-1+rpt1"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.21-1+rpt1": {
            "linux_commit": "0afb5e98488aed7017b9bf321b575d0177feb7ed",
            "upstream_version": "6.1.21",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.79"
          },
          "1:6.1.47-1+rpt2": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.79"
          },
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.79",
            "compiled_filter": false
          },
          "1:6.1.54-1+rpt2": {
            "linux_commit": "2906f7abdc03d4a92b6b0e2e0c87ea2a9dffe8f7",
            "upstream_version": "6.1.54",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.79"
          },
          "1:6.1.58-1+rpt2": {
            "linux_commit": "ccf1586ad0663fa91238ac56abf6340d6d740d18",
            "upstream_version": "6.1.58",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.79"
          },
          "1:6.1.63-1+rpt1": {
            "linux_commit": null,
            "upstream_version": "6.1.63",
            "assessment": "upstream version (no usable Linux commit)",
            "upstream_fixed": "6.1.79"
          },
          "1:6.1.73-1+rpt1": {
            "linux_commit": null,
            "upstream_version": "6.1.73",
            "assessment": "upstream version (no usable Linux commit)",
            "upstream_fixed": "6.1.79"
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2024-26689"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/8180d0c27b93a6eb60da1b08ea079e3926328214"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/70e329b440762390258a6fe8c0de93c9fdd56c77"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/f3f98d7d84b31828004545e29fd7262b9f444139"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/ae20db45e482303a20e56f2db667a9d9c54ac7e7"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7958c1bf5b03c6f1f58e724dbdec93f8f60b96fc"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/cda4672da1c26835dcbd7aec2bfed954eda9b5ef"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T11:52:36Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 8.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:N - The freeing half of the race executes in `handle_cap_grant()`/`ceph_fill_inode()` while parsing `CEPH_MSG_CLIENT_CAPS` messages and reply traces received from the remote Ceph MDS, so a co-tenant CephFS client, a malicious/compromised MDS, or a MITM on the (by-default unencrypted) msgr connection controls the timing and content of the free. The freed buffer's contents are additionally marshalled into `msg->middle` and transmitted back over the network to the MDS.\nAC:L - The attacker drives both sides of the race \u2014 local/co-tenant `setxattr` traffic opens the unlocked `__prep_cap()`\u2192`__send_cap()` window, while concurrent access to the same inode from another client forces the MDS to emit the cap grant with a higher `xattr_version` that drops the last reference \u2014 and the sequence can be retried without limit until the window is hit.\nPR:L - Exploitation requires only an ordinary unprivileged account with write access to a file on an already-mounted CephFS (no capabilities are checked anywhere on the `setxattr`\u2192`ceph_check_caps`\u2192`__prep_cap` path), or an equally unprivileged co-tenant account on the same shared CephFS.\nUI:N - No victim action is needed at exploit time; the CephFS mount is pre-existing deployment configuration, and the attacker's own syscalls and MDS traffic supply every step of the race.\nS:U - The corruption is confined to kernel heap objects within the same kernel security authority; no VM, IOMMU, or sandbox boundary is crossed.\nC:H - This is a use-after-free whose stale `vec.iov_base`/`vec.iov_len` are read back and sent to the MDS as the cap message middle section, leaking reallocated kernel heap contents to a remote peer, and heap grooming of the small `kmalloc-64` `ceph_buffer` object generalizes this into an arbitrary kernel-memory read.\nI:H - `ceph_buffer_get()` performs a `kref_get()` increment directly into freed memory, corrupting a refcount field of whatever object is reallocated into that slab slot, and the later `ceph_buffer_put()`/`kvfree()` on stale pointers yields a double-free/arbitrary-free \u2014 both standard stepping stones to arbitrary write and control-flow hijack.\nA:H - The use-after-free was caught by KASAN and, unmitigated, corrupts slab metadata and refcounts leading to oops, double-free and kernel panic, which the attacker can trigger repeatedly."
    }
  }
}