In the Linux kernel, the following vulnerability has been resolved: bpf: Fix missing migration protection in __rhtab_map_lookup_and_delete_batch()… (CVE-2026-98787)

The Linux kernel's BPF component had a missing migration protection in the __rhtab_map_lookup_and_delete_batch() function. The function calls rhtab_delete_elem() under rcu_read_lock(), which does not disable CPU migration on CONFIG_PREEMPT_RCU kernels. Since this_cpu_ptr() requires migration to be disabled, the task could migrate CPUs during the delete loop, triggering a kernel BUG related to smp_processor_id() usage in preemptible code. The patch adds migrate_disable()/migrate_enable() calls around the delete loop to align with protections used by other callers of rhtab_delete_elem().

This vulnerability could cause a kernel BUG due to improper CPU migration handling during BPF map element deletion, potentially leading to system instability or crashes. There is no indication of code execution or privilege escalation from the provided data.

A fix is available that adds migration disable/enable calls around the affected code section. Users should apply the official Linux kernel patches that address this issue. No alternative mitigations are indicated.