From 5c1a37653260ed5d9c8b26fb7fe7b99629612982 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Thu, 21 Dec 2023 19:18:01 -0800 Subject: bpf: Limit up to 512 bytes for bpf_global_percpu_ma allocation For percpu data structure allocation with bpf_global_percpu_ma, the maximum data size is 4K. But for a system with large number of cpus, bigger data size (e.g., 2K, 4K) might consume a lot of memory. For example, the percpu memory consumption with unit size 2K and 1024 cpus will be 2K * 1K * 1k = 2GB memory. We should discourage such usage. Let us limit the maximum data size to be 512 for bpf_global_percpu_ma allocation. Acked-by: Hou Tao Signed-off-by: Yonghong Song Link: https://lore.kernel.org/r/20231222031801.1290841-1-yonghong.song@linux.dev Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index e9699a2cfe4f..d5f4ff1eb235 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -195,6 +195,8 @@ struct bpf_verifier_stack_elem { POISON_POINTER_DELTA)) #define BPF_MAP_PTR(X) ((struct bpf_map *)((X) & ~BPF_MAP_PTR_UNPRIV)) +#define BPF_GLOBAL_PERCPU_MA_MAX_SIZE 512 + static int acquire_reference_state(struct bpf_verifier_env *env, int insn_idx); static int release_reference(struct bpf_verifier_env *env, int ref_obj_id); static void invalidate_non_owning_refs(struct bpf_verifier_env *env); @@ -12160,6 +12162,12 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, } if (meta.func_id == special_kfunc_list[KF_bpf_percpu_obj_new_impl]) { + if (ret_t->size > BPF_GLOBAL_PERCPU_MA_MAX_SIZE) { + verbose(env, "bpf_percpu_obj_new type size (%d) is greater than %d\n", + ret_t->size, BPF_GLOBAL_PERCPU_MA_MAX_SIZE); + return -EINVAL; + } + if (!bpf_global_percpu_ma_set) { mutex_lock(&bpf_percpu_ma_lock); if (!bpf_global_percpu_ma_set) { -- cgit