net/sched: cls_route: free emptied bucket on filter move
Summary
| CVE | CVE-2026-97959 |
|---|
| State | PUBLISHED |
|---|
| Assigner | Linux |
|---|
| Source Priority | CVE Program / NVD first with legacy fallback |
|---|
| Published | 2026-09-25 11:17:23 UTC |
|---|
| Updated | 2026-09-25 11:17:23 UTC |
|---|
| Description | In the Linux kernel, the following vulnerability has been resolved:
net/sched: cls_route: free emptied bucket on filter move
route4_change can move an existing filter to a different top-level
bucket: route4_set_parms recomputes the handle from TCA_ROUTE4_TO/
FROM/IIF, and the handle-mismatch check is gated on the 'new' flag, so
for an existing filter the new handle may differ from the old one and
land in a different bucket. When this happens, the filter is unlinked
from the old bucket, but the bucket itself is never freed once it goes
empty. The stale empty bucket remains in head->table[], causing
route4_delete to report *last=false even after the last live filter is
gone. That pins the empty tcf_proto and causes a leak.
Fix this by refcounting the filters linked to a bucket and freeing the
bucket when the count drops to zero. The existing scan in route4_delete
goes away with it.
The count is updated at all sites that link or unlink a filter during add,
change and delete, and the bucket is dropped from head->table[] as soon as
it reaches zero.
Conditions to recreate the bug:
CONFIG_NET_CLS_ROUTE4=y, CONFIG_NET_SCH_INGRESS=y, CONFIG_NET_CLS_ACT=y.
tc qdisc replace dev lo clsact
tc filter add dev lo ingress protocol ip pref 100 route from 1 to 1
tc filter change dev lo ingress protocol ip pref 100 handle 0x10001 \
route from 1 to 2
tc filter del dev lo ingress protocol ip pref 100 handle 0x10002 \
route from 1 to 2
tc filter show dev lo ingress | grep -c 'pref 100 route chain 0 ' |
|---|
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected 1e052be69d045c8d0f82ff1116fd3e5a79661745 2e2f130951d34871b0643bf700164d97cff4b427 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1e052be69d045c8d0f82ff1116fd3e5a79661745 f8495d67434e1cb7e511297687ca55fdb28e4c20 git |
Not specified |
| CNA |
Linux |
Linux |
affected 1e052be69d045c8d0f82ff1116fd3e5a79661745 81dd117c04422c6d0c7974aba9fa6a0ba370959b git |
Not specified |
| CNA |
Linux |
Linux |
affected 1e052be69d045c8d0f82ff1116fd3e5a79661745 1853f30cf5c84971f99788a76207c6f745380896 git |
Not specified |
| CNA |
Linux |
Linux |
affected 4.1 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 4.1 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.12.111 6.12.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.18.53 6.18.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.2.7 7.2.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.3-rc3 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/81dd117c04422c6d0c7974aba9fa6a0ba370959b |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/f8495d67434e1cb7e511297687ca55fdb28e4c20 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/2e2f130951d34871b0643bf700164d97cff4b427 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/1853f30cf5c84971f99788a76207c6f745380896 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.