BPF ringbuf assumes the size to be a multiple of page size and the power of
2 value. The latter is important to avoid division while calculating position
inside the ring buffer and using (N-1) mask instead. This patch fixes omission
to enforce power-of-2 size rule.
Fixes: 457f44363a88 ("bpf: Implement BPF ring buffer and verifier support for it")
Signed-off-by: Andrii Nakryiko <andriin@xxxxxx>
---
kernel/bpf/ringbuf.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index 180414bb0d3e..dcc8e8b9df10 100644
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c
@@ -132,7 +132,7 @@ static struct bpf_ringbuf *bpf_ringbuf_alloc(size_t data_sz, int numa_node)
{
struct bpf_ringbuf *rb;
- if (!data_sz || !PAGE_ALIGNED(data_sz))
+ if (!is_power_of_2(data_sz) || !PAGE_ALIGNED(data_sz))
return ERR_PTR(-EINVAL);
#ifdef CONFIG_64BIT
@@ -166,7 +166,8 @@ static struct bpf_map *ringbuf_map_alloc(union bpf_attr *attr)
return ERR_PTR(-EINVAL);
if (attr->key_size || attr->value_size ||
- attr->max_entries == 0 || !PAGE_ALIGNED(attr->max_entries))
+ !is_power_of_2(attr->max_entries) ||
+ !PAGE_ALIGNED(attr->max_entries))
return ERR_PTR(-EINVAL);
rb_map = kzalloc(sizeof(*rb_map), GFP_USER);
--
2.24.1
