Bug 2541416 (CVE-2026-100071)

Summary: CVE-2026-100071 kernel: net: hsr: free learned nodes on device setup failure
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security DevOps Team <prodsec-dev>
Status: NEW --- QA Contact:
Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone: ---Keywords: Security
Target Release: ---   
Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's High-availability Seamless Redundancy (HSR) networking subsystem. When device initialization fails after network receive handlers have already been registered, frames received during this setup window can create dynamic node entries that are not properly released during error cleanup. An attacker sending network traffic during a failed device setup could exploit this flaw to cause a memory leak, potentially resulting in kernel resource exhaustion and a Denial of Service (DoS).
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oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
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Description OSIDB Bzimport 2026-09-25 13:24:57 UTC 
In the Linux kernel, the following vulnerability has been resolved:

net: hsr: free learned nodes on device setup failure

hsr_dev_finalize() can fail after a lower-device RX handler has
already been registered (slave A is added before the failable slave B
and interlink adds). RX handlers run in softirq regardless of the
master's state, so frames received in that window can learn dynamic
nodes into node_db, and the error unwind never releases them.

Free both owned dynamic databases in the unwind, mirroring
hsr_dellink(). proxy_node_db is provably empty on every current error
exit (only interlink RX feeds it, and the interlink add is the last
failable step) and is freed for symmetry. The order is safe:
hsr_del_port() unregisters each RX handler with synchronize_net()
before hsr_del_nodes() runs, which removes remaining entries with
list_del_rcu() and defers their release with call_rcu() for readers
already under RCU.
Comment 1 Mauro Matteo Cascella 2026-09-30 16:47:35 UTC 
Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-100071.mbox