bpf: Reject redirect helpers without a bpf_net_context

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Summary

CVECVE-2026-68337
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-08-10 13:20:24 UTC
Updated2026-08-10 13:20:24 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: bpf: Reject redirect helpers without a bpf_net_context The bpf_redirect*() helpers and skb_do_redirect() obtain the per-task bpf_redirect_info via bpf_net_ctx_get_ri(), which dereferences the current->bpf_net_context unconditionally. That context is established on the paths that run tc BPF such as sch_handle_{ingress,egress}(), *except* for the case where {cls,act}_bpf was attached to a proper qdisc. A program running from there reaches the NULL deref in two ways: * It calls bpf_redirect() directly, which dereferences the context at the top of the helper: tc qdisc add dev eth0 root handle 1: red limit 1MB min 10KB max 20KB \ avpkt 1000 burst 100 qevent early_drop block 10 tc filter add block 10 pref 1 bpf obj redirect.o * It simply returns TC_ACT_REDIRECT without helper call: tcf_qevent_handle() then dispatches to skb_do_redirect(), which dereferences the context Rather than extending bpf_net_context management into the qdisc path, make the redirect helpers refuse to operate when no context exists, and have tcf_qevent_handle() drop a TC_ACT_REDIRECT verdict instead of calling skb_do_redirect(). Previous behaviour was a crash, so nothing regresses by not supporting it.

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected 3625750f05ecce21a0fce429c1ff85acfffb461b cabfacbd5af09d3ae898ca224c4a1459e9bba15d git Not specified
CNA Linux Linux affected 3625750f05ecce21a0fce429c1ff85acfffb461b 3f4920d165b29052255527d8ae7619e7ec132ece git Not specified
CNA Linux Linux affected 5.9 Not specified
CNA Linux Linux unaffected 5.9 semver Not specified
CNA Linux Linux unaffected 7.1.6 7.1.* semver Not specified
CNA Linux Linux unaffected 7.2-rc5 * original_commit_for_fix Not specified

References

ReferenceSourceLinkTags
git.kernel.org/stable/c/cabfacbd5af09d3ae898ca224c4a1459e9bba15d 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
git.kernel.org/stable/c/3f4920d165b29052255527d8ae7619e7ec132ece 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org
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