[PATCH AUTOSEL 4.19 01/16] bpf: Check percpu map value size first

[Sasha Levin <sashal@kernel.org>]

From: Tao Chen <chen.dylane@gmail.com>

[ Upstream commit 1d244784be6b01162b732a5a7d637dfc024c3203 ]

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
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 kernel/bpf/arraymap.c | 3 +++
 kernel/bpf/hashtab.c  | 3 +++
 2 files changed, 6 insertions(+)

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index 44f53c06629e2..03e244b11f5a0 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -71,6 +71,9 @@ int array_map_alloc_check(union bpf_attr *attr)
 		 * access the elements.
 		 */
 		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;
 }
diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 16081d8384bfc..bca3287030460 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -291,6 +291,9 @@ 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;
 }
-- 
2.43.0