From 1d244784be6b01162b732a5a7d637dfc024c3203 Mon Sep 17 00:00:00 2001 From: Tao Chen Date: Tue, 10 Sep 2024 22:41:10 +0800 Subject: [PATCH] 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 Signed-off-by: Tao Chen Signed-off-by: Andrii Nakryiko Acked-by: Jiri Olsa Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20240910144111.1464912-2-chen.dylane@gmail.com --- 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 a43e62e2a8bb..79660e3fca4c 100644 --- 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 45c7195b65ba..b14b87463ee0 100644 --- 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; }