bpf: Do not allow deleting local storage in NMI
- Published
- Last modified
- Where the record stands: published, rejected by its publisher, or superseded by another id.What do these mean? →
- published
- Whether CISA lists it in its Known Exploited Vulnerabilities catalog: proof that attackers are using it.What do these mean? →
- Not listed in CISA KEV
- Whether working attack code is public (Exploit-DB, Metasploit, Nuclei or GitHub). Public code makes attacks easier.What do these mean? →
- None on Exploit-DB, Metasploit or GitHub
Summary
In the Linux kernel, the following vulnerability has been resolved: bpf: Do not allow deleting local storage in NMI Currently, local storage may deadlock when deferring freeing selem or local storage through kfree_rcu(), call_rcu() or call_rcu_tasks_trace() in NMI or reentrant. Since deleting selem in NMI is an unlikely use case, partially mitigate it by returning error when calling from bpf_xxx_storage_delete() helpers in NMI. Note that, it is still possible to deadlock through reentrant. A full mitigation requires returning error when irqs_disabled() is true, which, however is too heavy-handed for bpf_xxx_storage_delete(). The long-term solution requires _nolock versions of call_rcu. Another possible solution is to defer the free through irq_work [0], but it would grow the size of selem, which is non-ideal. The check is only needed in bpf_selem_unlink(), which is used by helpers and syscalls. bpf_selem_unlink_nofail() is fine as it is called during map and owner tear down that never run in NMI or reentrant. [0] https://lore.kernel.org/bpf/20260205190233.912-1-alexei.starovoitov@gmail.com/
Timeline
- CVE published
Affected versions
- Linux Linux
Version range not reported
- Linux Linux
5.13