Bug 2502590 (CVE-2026-64123) - CVE-2026-64123 kernel: net: hsr: defer node table free until after RCU readers
Summary: CVE-2026-64123 kernel: net: hsr: defer node table free until after RCU readers
Keywords:
Status: NEW
Alias: CVE-2026-64123
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-07-19 17:07 UTC by OSIDB Bzimport
Modified: 2026-07-20 06:02 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
Last Closed:
Embargoed:


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Description OSIDB Bzimport 2026-07-19 17:07:47 UTC
In the Linux kernel, the following vulnerability has been resolved:

net: hsr: defer node table free until after RCU readers

HSR node-list and node-status generic-netlink operations run under
rcu_read_lock(). They walk hsr->node_db through hsr_get_next_node() and
hsr_get_node_data(), but RTM_DELLINK teardown removes the same node table
with plain list_del() and frees each node immediately.

That lets a generic-netlink reader hold a struct hsr_node pointer across
hsr_dellink(). In a KASAN build, widening the reader window after
hsr_get_next_node() obtains the node reproduces a slab-use-after-free
when the reader copies node->macaddress_A; the freeing stack is
hsr_del_nodes() from hsr_dellink().

Use list_del_rcu() and defer the free through the existing
hsr_free_node_rcu() callback. This matches the lifetime rule used by the
HSR prune paths, which already delete nodes with list_del_rcu() and
call_rcu().


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