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

diff --git a/kernel/bpf/arraymap.c b/kernel/bpf/arraymap.c
index a43e62e2a8bbe2f549061911477b172388b3329c..79660e3fca4c1b4c829f67210b9bfe22eb72eca7 100644 (file)
--- a/kernel/bpf/arraymap.c
+++ b/kernel/bpf/arraymap.c
@@ -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;
 }

diff --git a/kernel/bpf/hashtab.c b/kernel/bpf/hashtab.c
index 45c7195b65bada4ad055864540d147b84df9dd80..b14b87463ee04e8dddd29a835f80ab3049555908 100644 (file)
--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -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;
 }