| From b293dcc473d22a62dc6d78de2b15e4f49515db56 Mon Sep 17 00:00:00 2001 |
| From: Hou Tao <hotforest@gmail.com> |
| Date: Wed, 2 Feb 2022 14:01:58 +0800 |
| Subject: bpf: Use VM_MAP instead of VM_ALLOC for ringbuf |
| |
| 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 |
| @@ -108,7 +108,7 @@ 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; |