CVE-2026-90143: net: kcm: Hold RCU read lock while running BPF parser
In the Linux kernel, the following vulnerability has been resolved:
net: kcm: Hold RCU read lock while running BPF parser
kcmparsefuncstrparser() calls bpfprogrunpinoncpu() which prevents CPU migration, but does not establish an RCU read-side critical section. Consequently, BPF map operations can trigger WARNONONCE(!bpfrculockheld()) when called from the KCM strparser program.
Hold the RCU read lock while running the program.
Affected Software
Event History
Frequently Asked Questions
What conditions are required to trigger the warning?
A KCM strparser BPF program must run through kcm_parse_func_strparser() and perform BPF map operations. CPU pinning performed by bpf_prog_run_pin_on_cpu() does not itself establish the required RCU read-side critical section.
How can I determine whether the issue has occurred on a system?
The described symptom is a WARN_ON_ONCE(!bpf_rcu_lock_held()) warning triggered by BPF map operations from a KCM strparser program. Review kernel warnings for that condition in environments using KCM strparser BPF programs.
What is the remediation?
Apply a kernel update containing the fix that holds the RCU read lock while the KCM strparser BPF program runs. The provided stable kernel references identify commits carrying the fix.