diff options
| author | Hou Tao <houtao1@huawei.com> | 2023-07-04 15:40:14 +0800 |
|---|---|---|
| committer | Daniel Borkmann <daniel@iogearbox.net> | 2023-07-05 14:09:45 +0200 |
| commit | cf6eeb8f9dace014f63a3b2e959d0922bf737233 (patch) | |
| tree | d2efd5fe22d2bc2c637beab4c7a46268fcf77d64 | |
| parent | c20f9cef725bc6b19efe372696e8000fb5af0d46 (diff) | |
bpf: Remove unnecessary ring buffer size check
The theoretical maximum size of ring buffer is about 64GB, but now the
size of ring buffer is specified by max_entries in bpf_attr and its
maximum value is (4GB - 1), and it won't be possible for overflow.
So just remove the unnecessary size check in ringbuf_map_alloc() but
keep the comments for possible extension in future.
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Hou Tao <houtao1@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Closes: https://lore.kernel.org/bpf/9c636a63-1f3d-442d-9223-96c2dccb9469@moroto.mountain
Link: https://lore.kernel.org/bpf/20230704074014.216616-1-houtao@huaweicloud.com
| -rw-r--r-- | kernel/bpf/ringbuf.c | 26 |
1 files changed, 11 insertions, 15 deletions
diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c index 875ac9b698d9..f045fde632e5 100644 --- a/kernel/bpf/ringbuf.c +++ b/kernel/bpf/ringbuf.c @@ -23,15 +23,6 @@ #define RINGBUF_MAX_RECORD_SZ (UINT_MAX/4) -/* Maximum size of ring buffer area is limited by 32-bit page offset within - * record header, counted in pages. Reserve 8 bits for extensibility, and take - * into account few extra pages for consumer/producer pages and - * non-mmap()'able parts. This gives 64GB limit, which seems plenty for single - * ring buffer. - */ -#define RINGBUF_MAX_DATA_SZ \ - (((1ULL << 24) - RINGBUF_POS_PAGES - RINGBUF_PGOFF) * PAGE_SIZE) - struct bpf_ringbuf { wait_queue_head_t waitq; struct irq_work work; @@ -161,6 +152,17 @@ static void bpf_ringbuf_notify(struct irq_work *work) wake_up_all(&rb->waitq); } +/* Maximum size of ring buffer area is limited by 32-bit page offset within + * record header, counted in pages. Reserve 8 bits for extensibility, and + * take into account few extra pages for consumer/producer pages and + * non-mmap()'able parts, the current maximum size would be: + * + * (((1ULL << 24) - RINGBUF_POS_PAGES - RINGBUF_PGOFF) * PAGE_SIZE) + * + * This gives 64GB limit, which seems plenty for single ring buffer. Now + * considering that the maximum value of data_sz is (4GB - 1), there + * will be no overflow, so just note the size limit in the comments. + */ static struct bpf_ringbuf *bpf_ringbuf_alloc(size_t data_sz, int numa_node) { struct bpf_ringbuf *rb; @@ -193,12 +195,6 @@ static struct bpf_map *ringbuf_map_alloc(union bpf_attr *attr) !PAGE_ALIGNED(attr->max_entries)) return ERR_PTR(-EINVAL); -#ifdef CONFIG_64BIT - /* on 32-bit arch, it's impossible to overflow record's hdr->pgoff */ - if (attr->max_entries > RINGBUF_MAX_DATA_SZ) - return ERR_PTR(-E2BIG); -#endif - rb_map = bpf_map_area_alloc(sizeof(*rb_map), NUMA_NO_NODE); if (!rb_map) return ERR_PTR(-ENOMEM); |