bpf: Use VM_MAP instead of VM_ALLOC for ringbuf

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: bpf: Use VM_MAP instead of VM_ALLOC for ringbuf After commit 2fd3fb0be1d1 ("kasan, vmalloc: unpoison VM_ALLOC pages after mapping"), non-VM_ALLOC mappings will be marked as accessible in __get_vm_area_node() when KASAN is enabled. But now the flag for ringbuf area is VM_ALLOC, so KASAN will complain out-of-bound access after vmap() returns. Because the ringbuf area is created by mapping allocated pages, so use VM_MAP instead. After the change, info in /proc/vmallocinfo also changes from [start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmalloc user to [start]-[end] 24576 ringbuf_map_alloc+0x171/0x290 vmap user

References

• https://git.kernel.org/stable/c/6304a613a97d6dcd49b93fbad31e9f39d1e138d6
• https://git.kernel.org/stable/c/5e457aeab52a5947619e1f18047f4d2f3212b3eb
• https://git.kernel.org/stable/c/d578933f6226d5419af9306746efa1c693cbaf9c
• https://git.kernel.org/stable/c/b293dcc473d22a62dc6d78de2b15e4f49515db56