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CVE-2026-98622

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

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 5.10.271, 5.15.222, 6.1.189, 6.6.158, 6.12.112, and 2 more
None on Exploit-DB, Metasploit or GitHub

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 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.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • Linux Linux

    From 64ff70b80fd403110b67dd9f7184a604fdb0da43 · fixed in e8fcf3f08834e939b797311742ee72b1e2a08096; From 64ff70b80fd403110b67dd9f7184a604fdb0da43 · fixed in af475f599270e59313552e6c6f3af8507da672b8; From 64ff70b80fd403110b67dd9f7184a604fdb0da43 · fixed in 424ba52c0058deeb940d02cba52eb0aeb288db33; From 64ff70b80fd403110b67dd9f7184a604fdb0da43 · fixed in d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a; From 64ff70b80fd403110b67dd9f7184a604fdb0da43 · fixed in d805560ad69cb266d669341ca01e26bffb0d2c67; From 64ff70b80fd403110b67dd9f7184a604fdb0da43 · fixed in 00734f3684fcec42c319bedfe68a5d357c720b53; From 64ff70b80fd403110b67dd9f7184a604fdb0da43 · fixed in 650787233c2fd6e515a7c5f371019a9fa080ccd2; From 64ff70b80fd403110b67dd9f7184a604fdb0da43 · fixed in 47abe7a5c4eb53269aca3506446f851572a059a3

  • Linux Linux

    5.7

  • KernelLinux

    From 5.7.0 · fixed in 5.10.271; From 5.11.0 · fixed in 5.15.222; From 5.16.0 · fixed in 6.1.189; From 6.2.0 · fixed in 6.6.158; From 6.7.0 · fixed in 6.12.112; From 6.13.0 · fixed in 6.18.55; From 6.19.0 · fixed in 7.2.9

References 8

git.kernel.org