[PATCH AUTOSEL 5.10 01/26] bpf: Check percpu map value size first

Sasha Levin
2024-10-04T18:30:08Z

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 5102338129d5f..3d92e42c3895a 100644
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -74,6 +74,9 @@ 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 72bc5f5752543..4c7cab79d90e5 100644
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -404,6 +404,9 @@ 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