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net: sock: fix hardened usercopy panic in sock_recv_errqueue

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: net: sock: fix hardened usercopy panic in sock_recv_errqueue skbuff_fclone_cache was created without defining a usercopy region, [1] unlike skbuff_head_cache which properly whitelists the cb[] field. [2] This causes a usercopy BUG() when CONFIG_HARDENED_USERCOPY is enabled and the kernel attempts to copy sk_buff.cb data to userspace via sock_recv_errqueue() -> put_cmsg(). The crash occurs when: 1. TCP allocates an skb using alloc_skb_fclone() (from skbuff_fclone_cache) [1] 2. The skb is cloned via skb_clone() using the pre-allocated fclone [3] 3. The cloned skb is queued to sk_error_queue for timestamp reporting 4. Userspace reads the error queue via recvmsg(MSG_ERRQUEUE) 5. sock_recv_errqueue() calls put_cmsg() to copy serr->ee from skb->cb [4] 6. __check_heap_object() fails because skbuff_fclone_cache has no usercopy whitelist [5] When cloned skbs allocated from skbuff_fclone_cache are used in the socket error queue, accessing the sock_exterr_skb structure in skb->cb via put_cmsg() triggers a usercopy hardening violation: [ 5.379589] usercopy: Kernel memory exposure attempt detected from SLUB object 'skbuff_fclone_cache' (offset 296, size 16)! [ 5.382796] kernel BUG at mm/usercopy.c:102! [ 5.383923] Oops: invalid opcode: 0000 [#1] SMP KASAN NOPTI [ 5.384903] CPU: 1 UID: 0 PID: 138 Comm: poc_put_cmsg Not tainted 6.12.57 #7 [ 5.384903] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.16.3-0-g

Announced Source revision 1
Original source ↗

CVE-2026-22977

Primary source · Revision 1

Imported from structured advisory data. Source references identify upstream records or fields; verify affected versions and your deployed configuration.

Security context

Source reference: cve:CVE-2026-22977

Linux

Source reference: /containers/cna/affected/0/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Linux

Source reference: /containers/cna/affected/1/product

Affected versions
Not stated in this record
Fixed versions
Not stated in this record
Prerequisites
Not stated in this record

Structured affected-version data

Original package identities and version rules from this source.

[
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
        "lessThan": "88dd6be7ebb3153b662c2cebcb06e032a92857f5",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
        "lessThan": "c655d2167bf014d4c61b4faeca59b60ff9b9f6b1",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
        "lessThan": "8c6901aa29626e35045130bac09b75f791acca85",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
        "lessThan": "582a5e922a9652fcbb7d0165c95d5b20aa37575d",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
        "lessThan": "005671c60fcf1dbdb8bddf12a62568fd5e4ec391",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
        "lessThan": "e00b169eaac5f7cdbf710c354c8fa76d02009115",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "6d07d1cd300f4c7e16005f881fea388164999cc8",
        "lessThan": "2a71a1a8d0ed718b1c7a9ac61f07e5755c47ae20",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/core/sock.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.16"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.16",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.248",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.198",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.161",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.121",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.66",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.6",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/core/sock.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-22977

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#39718 · Revision 1
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