From: Hou Tao <hotforest@xxxxxxxxx>
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@xxxxxxxxxxxxxxxxxxxxxxxxx
Signed-off-by: Hou Tao <houtao1@xxxxxxxxxx>
Signed-off-by: Andrii Nakryiko <andrii@xxxxxxxxxx>
Link: https://lore.kernel.org/bpf/20220202060158.6260-1-houtao1@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
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;
