Commit 1d244784 authored Sep 10, 2024 by Tao Chen Committed by Andrii Nakryiko Sep 11, 2024

bpf: Check percpu map value size first

Percpu map is often used, but the map value size limit often ignored,
like issue: https://github.com/iovisor/bcc/issues/2519

. Actually,
percpu map value size is bound by PCPU_MIN_UNIT_SIZE, so we
can check the value size whether it exceeds PCPU_MIN_UNIT_SIZE first,
like percpu map of local_storage. Maybe the error message seems clearer
compared with "cannot allocate memory".

Signed-off-by: Jinke Han <jinkehan@didiglobal.com>
Signed-off-by: Tao Chen <chen.dylane@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20240910144111.1464912-2-chen.dylane@gmail.com

parent 300a90b2

kernel/bpf/arraymap.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -73,6 +73,9 @@ int array_map_alloc_check(union bpf_attr *attr)
		/* avoid overflow on round_up(map->value_size) */
		if (attr->value_size > INT_MAX)
		return -E2BIG;
		/* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */
		if (percpu && round_up(attr->value_size, 8) > PCPU_MIN_UNIT_SIZE)
		return -E2BIG;

		return 0;
		}

kernel/bpf/hashtab.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -462,6 +462,9 @@ static int htab_map_alloc_check(union bpf_attr *attr)
		* kmalloc-able later in htab_map_update_elem()
		*/
		return -E2BIG;
		/* percpu map value size is bound by PCPU_MIN_UNIT_SIZE */
		if (percpu && round_up(attr->value_size, 8) > PCPU_MIN_UNIT_SIZE)
		return -E2BIG;

		return 0;
		}