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net/sched: cls_flow: fix NULL pointer dereference on shared blocks

Type: advisorySource: Official CVE List1 source record

In the Linux kernel, the following vulnerability has been resolved: net/sched: cls_flow: fix NULL pointer dereference on shared blocks flow_change() calls tcf_block_q() and dereferences q->handle to derive a default baseclass. Shared blocks leave block->q NULL, causing a NULL deref when a flow filter without a fully qualified baseclass is created on a shared block. Check tcf_block_shared() before accessing block->q and return -EINVAL for shared blocks. This avoids the null-deref shown below: ======================================================================= KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f] RIP: 0010:flow_change (net/sched/cls_flow.c:508) Call Trace: tc_new_tfilter (net/sched/cls_api.c:2432) rtnetlink_rcv_msg (net/core/rtnetlink.c:6980) [...] =======================================================================

Announced Source revision 1
Original source ↗

CVE-2026-31422

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-2026-31422

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": "1abf272022cf1d18469405f47b4ec49c6a3125db",
        "lessThan": "57f94ac7e953eece5ed4819605a18f3cdfc63dcc",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
        "lessThan": "942813276edeb1741fa5b0a73471beb4e495fa08",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
        "lessThan": "cc707a4fd4c3b6ab2722e06bc359aa010e13d408",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
        "lessThan": "4a09f72007201c9f667dc47f64517ec23eea65e5",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
        "lessThan": "9bf5fc36a43f7b8b5507c96e74fb81f1e8b4957e",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
        "lessThan": "a208c3e1232997e9317887294c20008dfcb75449",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
        "lessThan": "415ea0c973c754b9f375225807810eb9045f4293",
        "versionType": "git"
      },
      {
        "status": "affected",
        "version": "1abf272022cf1d18469405f47b4ec49c6a3125db",
        "lessThan": "1a280dd4bd1d616a01d6ffe0de284c907b555504",
        "versionType": "git"
      }
    ],
    "programFiles": [
      "net/sched/cls_flow.c"
    ],
    "defaultStatus": "unaffected"
  },
  {
    "repo": "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git",
    "vendor": "Linux",
    "product": "Linux",
    "versions": [
      {
        "status": "affected",
        "version": "4.15"
      },
      {
        "status": "unaffected",
        "version": "0",
        "lessThan": "4.15",
        "versionType": "semver"
      },
      {
        "status": "unaffected",
        "version": "5.10.253",
        "versionType": "semver",
        "lessThanOrEqual": "5.10.*"
      },
      {
        "status": "unaffected",
        "version": "5.15.203",
        "versionType": "semver",
        "lessThanOrEqual": "5.15.*"
      },
      {
        "status": "unaffected",
        "version": "6.1.168",
        "versionType": "semver",
        "lessThanOrEqual": "6.1.*"
      },
      {
        "status": "unaffected",
        "version": "6.6.134",
        "versionType": "semver",
        "lessThanOrEqual": "6.6.*"
      },
      {
        "status": "unaffected",
        "version": "6.12.81",
        "versionType": "semver",
        "lessThanOrEqual": "6.12.*"
      },
      {
        "status": "unaffected",
        "version": "6.18.22",
        "versionType": "semver",
        "lessThanOrEqual": "6.18.*"
      },
      {
        "status": "unaffected",
        "version": "6.19.12",
        "versionType": "semver",
        "lessThanOrEqual": "6.19.*"
      },
      {
        "status": "unaffected",
        "version": "7.0",
        "versionType": "original_commit_for_fix",
        "lessThanOrEqual": "*"
      }
    ],
    "programFiles": [
      "net/sched/cls_flow.c"
    ],
    "defaultStatus": "affected"
  }
]
Related CVEs
CVE-2026-31422

Source reference: /cveMetadata/cveId

Publisher severity

No explicit severity was provided.

Event
#28273 · Revision 1
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Publisher date
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