CVE-2022-48714

What it actually does

Incorrect VM_ALLOC flag on BPF ringbuf vmap allocation prevents KASAN from properly unpoisoning mapped pages, producing false out-of-bounds access reports after vmap returns.

Why it matters to the business

Kernel developers and security scanners using KASAN-enabled builds see spurious warnings or potential stability issues when BPF ring buffers are used, increasing triage effort on affected Linux distributions.

How an attack unfolds

An attacker would need to trigger ringbuf allocation under KASAN, but the flaw is a diagnostic compatibility issue rather than a direct memory corruption primitive; no public exploitation chains are known.

How to fix it

Upgrade to a kernel containing commit 6304a613a97d6dcd49b93fbad31e9f39d1e138d6 or later; rebuild with the corrected VM_MAP flag for ringbuf areas.

How to confirm the fix worked

Confirm the presence of commit 6304a613a97d6dcd49b93fbad31e9f39d1e138d6 in the running kernel source and verify /proc/vmallocinfo shows vmap user instead of vmalloc user for ringbuf_map_alloc entries.

Typical attack path

1. Load or attach a BPF program that allocates a ringbuf map
2. Trigger vmap of the underlying pages while KASAN is active
3. Observe KASAN report or kernel behavior change due to incorrect VM flag

How to detect it

Review kernel logs for KASAN reports referencing ringbuf_map_alloc or vmalloc/vmap transitions; inspect /proc/vmallocinfo for legacy vmalloc user entries on ringbuf allocations.

What your security team should do

• Prioritize patching production kernels that enable KASAN or run BPF workloads
• Update build pipelines to include the fixed commit before enabling KASAN testing
• Monitor for any downstream distribution backports of 6304a613a97d