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CVE-2026-72368 (GCVE-0-2026-72368)

Vulnerability from cvelistv5 – Published: 2026-08-15 05:56 – Updated: 2026-08-17 05:43
VLAI
Title
cachefiles: Fix double unlock in nomem_d_alloc error path
Summary
In the Linux kernel, the following vulnerability has been resolved: cachefiles: Fix double unlock in nomem_d_alloc error path When start_creating() fails and returns -ENOMEM, it has already released the parent directory lock in __start_dirop(): static struct dentry *__start_dirop(...) { ... inode_lock_nested(dir, I_MUTEX_PARENT); dentry = lookup_one_qstr_excl(name, parent, lookup_flags); if (IS_ERR(dentry)) inode_unlock(dir); <-- Lock released on error return dentry; } However, the nomem_d_alloc error path in cachefiles_get_directory() unconditionally calls inode_unlock(d_inode(dir)) again, causing a double unlock that corrupts the rwsem state. This is a leftover from commit 7ab96df840e60 which replaced manual locking with start_creating() but failed to update the nomem_d_alloc path (while correctly updating mkdir_error and lookup_error paths).
Severity
7.8 (High)
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Assigner
References
Impacted products
Vendor Product Version CPE status
Linux Linux Affected: 7ab96df840e60eb933abfe65fc5fe44e72f16dc0 , < 26757dac15175f2a42e3537f1ba86e62456d48f1 (git)
Affected: 7ab96df840e60eb933abfe65fc5fe44e72f16dc0 , < 8c256fba2b46020004201c500b2a1fbc707a33ef (git)
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Linux Linux Affected: 6.19
Unaffected: 0 , < 6.19 (semver)
Unaffected: 7.1.5 , ≤ 7.1.* (semver)
Unaffected: 7.2 , ≤ * (original_commit_for_fix)
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          "product": "Linux",
          "programFiles": [
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          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\ncachefiles: Fix double unlock in nomem_d_alloc error path\n\nWhen start_creating() fails and returns -ENOMEM, it has already\nreleased the parent directory lock in __start_dirop():\n\n    static struct dentry *__start_dirop(...)\n    {\n        ...\n        inode_lock_nested(dir, I_MUTEX_PARENT);\n        dentry = lookup_one_qstr_excl(name, parent, lookup_flags);\n        if (IS_ERR(dentry))\n            inode_unlock(dir);  \u003c-- Lock released on error\n        return dentry;\n    }\n\nHowever, the nomem_d_alloc error path in cachefiles_get_directory()\nunconditionally calls inode_unlock(d_inode(dir)) again, causing a\ndouble unlock that corrupts the rwsem state.\n\nThis is a leftover from commit 7ab96df840e60 which replaced manual\nlocking with start_creating() but failed to update the nomem_d_alloc\npath (while correctly updating mkdir_error and lookup_error paths)."
        }
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            "version": "3.1"
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          "scenarios": [
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              "lang": "en",
              "value": "AV:L - The flaw is in cachefiles VFS directory creation reached only via local `/dev/cachefiles` ioctl/bind or local NFS/CIFS/9p fscache volume setup during mount, not from remote packet handling like nfsd or ksmbd.\nAC:L - Triggering requires only a `-ENOMEM` from `start_creating()` during `cachefiles_get_directory()`, which an attacker can reliably force with local memory pressure or repeated bind/mount attempts; no uncontrollable race or rare layout is needed once CACHEFILES is active.\nPR:L - Exploitation needs `CAP_SYS_ADMIN` to open `/dev/cachefiles` and bind the cache, or to mount a network filesystem with fscache while cachefilesd is running; both are obtainable in an unprivileged user namespace, not solely init-namespace root.\nUI:N - No separate victim action is required beyond attacker-controlled local steps (opening `/dev/cachefiles`, binding, or mounting with fscache under memory pressure); cachefilesd does not need a user to click or open a file.\nS:U - Corrupting a backing-directory inode rwsem affects kernel/VFS locking within the same host security boundary and does not cross VM, IOMMU, or container hypervisor isolation by itself.\nC:H - Double-unlocking the parent directory rwsem corrupts kernel lock state and can leave the inode lock inconsistent, enabling concurrent VFS access and memory corruption primitives that may disclose kernel memory under kernel guidance for lock corruption bugs.\nI:H - Rwsem corruption breaks directory serialization, allowing unsynchronized create/lookup/mkdir operations on cache backing storage and creating conditions for further VFS metadata corruption or control-flow manipulation consistent with high integrity impact.\nA:H - An extra `inode_unlock()` on an already-released rwsem corrupts lock owner/count state and commonly produces DEBUG_RWSEMS warnings, oopses, or kernel panics, matching high availability impact for kernel crash bugs."
            }
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        "dateUpdated": "2026-08-17T05:43:22.072Z",
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        "shortName": "Linux"
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          "url": "https://git.kernel.org/stable/c/26757dac15175f2a42e3537f1ba86e62456d48f1"
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        {
          "url": "https://git.kernel.org/stable/c/8c256fba2b46020004201c500b2a1fbc707a33ef"
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    "cveId": "CVE-2026-72368",
    "datePublished": "2026-08-15T05:56:05.329Z",
    "dateReserved": "2026-08-09T03:40:39.922Z",
    "dateUpdated": "2026-08-17T05:43:22.072Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
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      "current_release_date": "2026-08-19T17:43:22+00:00",
      "cve": "CVE-2026-72368",
      "id": "CVE-2026-72368",
      "initial_release_date": "2026-08-15T00:00:00+00:00",
      "product_status:known_affected": "14",
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      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: cachefiles: Fix double unlock in nomem_d_alloc error path",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-72368.json",
      "version": "3"
    }
  }
}



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