HighFix available

ceph: prevent use-after-free in encode_cap_msg()

Type: advisorySources: OSV

In the Linux kernel, the following vulnerability has been resolved: ceph: prevent use-after-free in encode_cap_msg() In fs/ceph/caps.c, in encode_cap_msg(), "use after free" error was caught by KASAN at this line - 'ceph_buffer_get(arg->xattr_buf);'. This implies before the refcount could be increment here, it was freed. In same file, in "handle_cap_grant()" refcount is decremented by this line - 'ceph_buffer_put(ci->i_xattrs.blob);'. It appears that a race occurred and resource was freed by the latter line before the former line could increment it. encode_cap_msg() is called by __send_cap() and __send_cap() is called by ceph_check_caps() after calling __prep_cap(). __prep_cap() is where arg->xattr_buf is assigned to ci->i_xattrs.blob. This is the spot where the refcount must be increased to prevent "use after free" error.

Products: Kernel
Affected versions: Not specified
Fixed versions: 5.10.210, 5.15.149, 6.1.79, 6.6.18, 6.7.6
CVEs: CVE-2024-26689
Confirmed fixed CVEs: Not specified
Updated in this feed: 2 Nov 2026, 19:01 UTC · Revision 1

Source evidence

ceph: prevent use-after-free in encode_cap_msg()

core-osv · Original source

Published 3 Apr 2024, 14:54 UTC

osv:CVE-2024-26689

Kernel

Fixed versions: 5.10.210, 5.15.149, 6.1.79, 6.6.18, 6.7.6

Complete source record

{
  "id": "c7f5a0e0d72688017794749d36dfa09a0b0c80c3f297f7a2781b9d915b334140",
  "url": "https://osv.dev/vulnerability/CVE-2024-26689",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ceph: prevent use-after-free in encode_cap_msg()",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ceph: prevent use-after-free in encode_cap_msg() In fs/ceph/caps.c, in encode_cap_msg(), \"use after free\" error was caught by KASAN at this line - 'ceph_buffer_get(arg->xattr_buf);'. This implies before the refcount could be increment here, it was freed. In same file, in \"handle_cap_grant()\" refcount is decremented by this line - 'ceph_buffer_put(ci->i_xattrs.blob);'. It appears that a race occurred and resource was freed by the latter line before the former line could increment it. encode_cap_msg() is called by __send_cap() and __send_cap() is called by ceph_check_caps() after calling __prep_cap(). __prep_cap() is where arg->xattr_buf is assigned to ci->i_xattrs.blob. This is the spot where the refcount must be increased to prevent \"use after free\" error.",
    "evidence": "osv:CVE-2024-26689",
    "products": [
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      "metrics": [
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      "modified": "2026-10-28T02:30:22.747320208Z",
      "provider": "osv",
      "references": [
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        "https://lists.debian.org/debian-lts-announce/2024/06/msg00017.html",
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  "source_id": "core-osv",
  "document_id": 488920,
  "published_at": "2024-04-03T14:54:50.885+00:00"
}