CVEvulnerability
CVE-2026-98622
- Status
- Received
- Published
- 2026-10-18
- Last modified
- 2026-10-19
- Assigner
- 416baaa9-dc9f-4396-8d5f-8c081fb06d67
Description
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.
References
- https://git.kernel.org/stable/c/00734f3684fcec42c319bedfe68a5d357c720b53 git.kernel.org
- https://git.kernel.org/stable/c/424ba52c0058deeb940d02cba52eb0aeb288db33 git.kernel.org
- https://git.kernel.org/stable/c/47abe7a5c4eb53269aca3506446f851572a059a3 git.kernel.org
- https://git.kernel.org/stable/c/650787233c2fd6e515a7c5f371019a9fa080ccd2 git.kernel.org
- https://git.kernel.org/stable/c/af475f599270e59313552e6c6f3af8507da672b8 git.kernel.org
- https://git.kernel.org/stable/c/d512c484bd93a5f2794aa03c9faeb7bcb82dbd4a git.kernel.org
- https://git.kernel.org/stable/c/d805560ad69cb266d669341ca01e26bffb0d2c67 git.kernel.org
- https://git.kernel.org/stable/c/e8fcf3f08834e939b797311742ee72b1e2a08096 git.kernel.org