From: Hou Tao hotforest@gmail.com
commit b293dcc473d22a62dc6d78de2b15e4f49515db56 upstream.
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
Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it") Reported-by: syzbot+5ad567a418794b9b5983@syzkaller.appspotmail.com Signed-off-by: Hou Tao houtao1@huawei.com Signed-off-by: Andrii Nakryiko andrii@kernel.org Link: https://lore.kernel.org/bpf/20220202060158.6260-1-houtao1@huawei.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- kernel/bpf/ringbuf.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/bpf/ringbuf.c +++ b/kernel/bpf/ringbuf.c @@ -104,7 +104,7 @@ static struct bpf_ringbuf *bpf_ringbuf_a }
rb = vmap(pages, nr_meta_pages + 2 * nr_data_pages, - VM_ALLOC | VM_USERMAP, PAGE_KERNEL); + VM_MAP | VM_USERMAP, PAGE_KERNEL); if (rb) { kmemleak_not_leak(pages); rb->pages = pages;