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authorAndrii Nakryiko <andriin@fb.com>2020-06-29 23:15:00 -0700
committerDaniel Borkmann <daniel@iogearbox.net>2020-06-30 16:31:55 +0200
commit517bbe1994a3cee29a35c730662277bb5daff582 (patch)
treee1c863b9b31b8101e280f2c8b8a5b1443f274c74
parent7e0245753f1794f17de472dcf4694fa5ed527384 (diff)
bpf: Enforce BPF ringbuf size to be the power of 2
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@fb.com> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Link: https://lore.kernel.org/bpf/20200630061500.1804799-1-andriin@fb.com
-rw-r--r--kernel/bpf/ringbuf.c18
1 files changed, 8 insertions, 10 deletions
diff --git a/kernel/bpf/ringbuf.c b/kernel/bpf/ringbuf.c
index 180414bb0d3e..0af88bbc1c15 100644
--- a/kernel/bpf/ringbuf.c
+++ b/kernel/bpf/ringbuf.c
@@ -132,15 +132,6 @@ 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))
- return ERR_PTR(-EINVAL);
-
-#ifdef CONFIG_64BIT
- /* on 32-bit arch, it's impossible to overflow record's hdr->pgoff */
- if (data_sz > RINGBUF_MAX_DATA_SZ)
- return ERR_PTR(-E2BIG);
-#endif
-
rb = bpf_ringbuf_area_alloc(data_sz, numa_node);
if (!rb)
return ERR_PTR(-ENOMEM);
@@ -166,9 +157,16 @@ 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);
+#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 = kzalloc(sizeof(*rb_map), GFP_USER);
if (!rb_map)
return ERR_PTR(-ENOMEM);