CVE-2026-74354bpf: Take mmap_lock in zap_pages()

Official description

In the Linux kernel, the following vulnerability has been resolved: bpf: Take mmap_lock in zap_pages() zap_vma_range() requires the owning mm's mmap_lock to be held. Taking mmap_read_lock under arena->lock would AB-BA against arena_vm_close() and arena_map_mmap(), both of which run with mmap_write_lock held and then acquire arena->lock. Instead drop arena->lock, mmget_not_zero() the vma's mm, take mmap_read_lock, and re-resolve the vma via find_vma() since it may have been unmapped or replaced while waiting. Track processed vmls with a per-call generation in vml->zap_gen and serialize zap_pages() callers with a new arena->zap_mutex so concurrent callers on different uaddr ranges do not mark each other's vmls processed before the zap is done.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/36b1d997866f6083d33934983aa2ce0a184ed642
• https://git.kernel.org/stable/c/80b89d0226a05e8b67969de99c31b51fcd54f76a