In the Linux kernel, the following vulnerability has been resolved:
net: openvswitch: fix use-after-free of the flow table mask array
tbl_mask_array_realloc() retires the old mask_array before it stops being
reachable:
old = ovsl_dereference(tbl->mask_array);
if (old) {
...
call_rcu(&old->rcu, mask_array_rcu_cb);
}
rcu_assign_pointer(tbl->mask_array, new);
call_rcu() only waits for read-side critical sections already in flight.
tbl->mask_array still points at old between the call_rcu() and the
rcu_assign_pointer(), so a reader entering ovs_flow_tbl_lookup_stats() in
that window picks up old in a fresh critical section that the pending
grace period does not cover.
tbl_mask_array_realloc() runs in process context under ovs_mutex, so the
window is preemptible and can outlast the grace period. Then
mask_array_rcu_cb() frees old before the swap runs:
BUG: KASAN: slab-use-after-free in flow_lookup.constprop.0+0x2bf/0x2f0
Read of size 8 at addr ffff888020b3e018 by task poc/741
flow_lookup.constprop.0+0x2bf/0x2f0
ovs_flow_tbl_lookup_stats+0x4a3/0x5c0
ovs_dp_process_packet+0x19c/0x710
ovs_vport_receive+0x243/0x390
internal_dev_xmit+0x81/0x170
Freed by task 728:
kfree+0x16a/0x4e0
rcu_core+0x853/0x1030
Publish the new array before retiring the old one. The kfree_rcu() that
call_rcu() replaced ran after the swap.
net: openvswitch: fix use-after-free of the flow table mask array
tbl_mask_array_realloc() retires the old mask_array before it stops being
reachable:
old = ovsl_dereference(tbl->mask_array);
if (old) {
...
call_rcu(&old->rcu, mask_array_rcu_cb);
}
rcu_assign_pointer(tbl->mask_array, new);
call_rcu() only waits for read-side critical sections already in flight.
tbl->mask_array still points at old between the call_rcu() and the
rcu_assign_pointer(), so a reader entering ovs_flow_tbl_lookup_stats() in
that window picks up old in a fresh critical section that the pending
grace period does not cover.
tbl_mask_array_realloc() runs in process context under ovs_mutex, so the
window is preemptible and can outlast the grace period. Then
mask_array_rcu_cb() frees old before the swap runs:
BUG: KASAN: slab-use-after-free in flow_lookup.constprop.0+0x2bf/0x2f0
Read of size 8 at addr ffff888020b3e018 by task poc/741
flow_lookup.constprop.0+0x2bf/0x2f0
ovs_flow_tbl_lookup_stats+0x4a3/0x5c0
ovs_dp_process_packet+0x19c/0x710
ovs_vport_receive+0x243/0x390
internal_dev_xmit+0x81/0x170
Freed by task 728:
kfree+0x16a/0x4e0
rcu_core+0x853/0x1030
Publish the new array before retiring the old one. The kfree_rcu() that
call_rcu() replaced ran after the swap.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | |||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
|
|||||||||||||||||||||
| Linux | Linux | affected |
|
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Advisories
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Fixes
Solution
No solution given by the vendor.
Workaround
No workaround given by the vendor.
References
History
Fri, 25 Sep 2026 10:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: net: openvswitch: fix use-after-free of the flow table mask array tbl_mask_array_realloc() retires the old mask_array before it stops being reachable: old = ovsl_dereference(tbl->mask_array); if (old) { ... call_rcu(&old->rcu, mask_array_rcu_cb); } rcu_assign_pointer(tbl->mask_array, new); call_rcu() only waits for read-side critical sections already in flight. tbl->mask_array still points at old between the call_rcu() and the rcu_assign_pointer(), so a reader entering ovs_flow_tbl_lookup_stats() in that window picks up old in a fresh critical section that the pending grace period does not cover. tbl_mask_array_realloc() runs in process context under ovs_mutex, so the window is preemptible and can outlast the grace period. Then mask_array_rcu_cb() frees old before the swap runs: BUG: KASAN: slab-use-after-free in flow_lookup.constprop.0+0x2bf/0x2f0 Read of size 8 at addr ffff888020b3e018 by task poc/741 flow_lookup.constprop.0+0x2bf/0x2f0 ovs_flow_tbl_lookup_stats+0x4a3/0x5c0 ovs_dp_process_packet+0x19c/0x710 ovs_vport_receive+0x243/0x390 internal_dev_xmit+0x81/0x170 Freed by task 728: kfree+0x16a/0x4e0 rcu_core+0x853/0x1030 Publish the new array before retiring the old one. The kfree_rcu() that call_rcu() replaced ran after the swap. | |
| Title | net: openvswitch: fix use-after-free of the flow table mask array | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-09-25T10:22:20.827Z
Reserved: 2026-09-24T16:01:01.158Z
Link: CVE-2026-97611
Vulnrichment
No data.
NVD
Status : Received
Published: 2026-09-25T11:17:15.213
Modified: 2026-09-25T11:17:15.213
Link: CVE-2026-97611
Redhat
No data.
OpenCVE Enrichment
No data.
Weaknesses
No weakness.