---
id: CVE-2026-98622
title: 'net/sched: act_ct: don''t WARN on benign flow_offload_alloc() failure'
summary: |-
  In the Linux kernel, the following vulnerability has been resolved:

  net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure

  flow_offload_alloc() returns NULL when the conntrack entry is dying
  (e.g. raced with a conntrack f…
severity: none
vendor: Linux
product: Linux
affected:
  - >-
    Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 <
    e8fcf3f08834e939b797311742ee72b1e2a08096
  - >-
    Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 <
    af475f599270e59313552e6c6f3af8507da672b8
  - >-
    Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 <
    424ba52c0058deeb940d02cba52eb0aeb288db33
  - >-
    Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 <
    d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a
  - >-
    Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 <
    d805560ad69cb266d669341ca01e26bffb0d2c67
  - >-
    Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 <
    00734f3684fcec42c319bedfe68a5d357c720b53
  - >-
    Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 <
    650787233c2fd6e515a7c5f371019a9fa080ccd2
  - >-
    Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 <
    47abe7a5c4eb53269aca3506446f851572a059a3
  - Linux 5.7
published: '2026-10-18'
updated: '2026-10-18'
sourceUpdated: '2026-10-18T15:19:42.514Z'
source: CVEORG
sourceUrl: 'https://www.cve.org/CVERecord?id=CVE-2026-98622'
references:
  - url: 'https://git.kernel.org/stable/c/e8fcf3f08834e939b797311742ee72b1e2a08096'
  - url: 'https://git.kernel.org/stable/c/af475f599270e59313552e6c6f3af8507da672b8'
  - url: 'https://git.kernel.org/stable/c/424ba52c0058deeb940d02cba52eb0aeb288db33'
  - url: 'https://git.kernel.org/stable/c/d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a'
  - url: 'https://git.kernel.org/stable/c/d805560ad69cb266d669341ca01e26bffb0d2c67'
  - url: 'https://git.kernel.org/stable/c/00734f3684fcec42c319bedfe68a5d357c720b53'
  - url: 'https://git.kernel.org/stable/c/650787233c2fd6e515a7c5f371019a9fa080ccd2'
  - url: 'https://git.kernel.org/stable/c/47abe7a5c4eb53269aca3506446f851572a059a3'
tags:
  - cve.org
ingestedAt: '2026-10-18T15:45:12.237Z'
---

## Overview

In the Linux kernel, the following vulnerability has been resolved:

net/sched: act_ct: don't WARN on benign flow_offload_alloc() failure

flow_offload_alloc() returns NULL when the conntrack entry is dying
(e.g. raced with a conntrack flush) or when the GFP_ATOMIC allocation
fails; both are expected under load and neither is a kernel bug. This
path runs from softirq on every committed packet, so with
panic_on_warn=1 an unprivileged user can panic the box just by racing
a conntrack flush against a `tc ... action ct commit` classifier.

Reproduced with a custom repro under QEMU: a small, fixed set of UDP
flows through `tc filter ... action ct commit` on lo, raced against
threads flooding bare ctnetlink CT_DELETE (flush) requests. Hits
WARNING: net/sched/act_ct.c:437 (tcf_ct_flow_table_add(), inlined
into tcf_ct_act() in this build) within ~15s on the unpatched kernel;
same setup is clean on the patched kernel. The fix itself is
behavior-preserving: both branches already did `goto err_alloc`
before and after, only the WARN is removed.

## Affected

- `Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 < e8fcf3f08834e939b797311742ee72b1e2a08096`
- `Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 < af475f599270e59313552e6c6f3af8507da672b8`
- `Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 < 424ba52c0058deeb940d02cba52eb0aeb288db33`
- `Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 < d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a`
- `Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 < d805560ad69cb266d669341ca01e26bffb0d2c67`
- `Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 < 00734f3684fcec42c319bedfe68a5d357c720b53`
- `Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 < 650787233c2fd6e515a7c5f371019a9fa080ccd2`
- `Linux >= 64ff70b80fd403110b67dd9f7184a604fdb0da43 < 47abe7a5c4eb53269aca3506446f851572a059a3`
- `Linux 5.7`

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.