From e58aac1a9a179fa9dab3025ef955cdb548c439f2 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Sat, 16 Dec 2023 11:55:10 +0800 Subject: selftests/bpf: Test the release of map btf When there is bpf_list_head or bpf_rb_root field in map value, the free of map btf and the free of map value may run concurrently and there may be use-after-free problem, so add two test cases to demonstrate it. And the use-after-free problem can been easily reproduced by using bpf_next tree and a KASAN-enabled kernel. The first test case tests the racing between the free of map btf and the free of array map. It constructs the racing by releasing the array map in the end after other ref-counter of map btf has been released. To delay the free of array map and make it be invoked after btf_free_rcu() is invoked, it stresses system_unbound_wq by closing multiple percpu array maps before it closes the array map. The second case tests the racing between the free of map btf and the free of inner map. Beside using the similar method as the first one does, it uses bpf_map_delete_elem() to delete the inner map and to defer the release of inner map after one RCU grace period. The reason for using two skeletons is to prevent the release of outer map and inner map in map_in_map_btf.c interfering the release of bpf map in normal_map_btf.c. Signed-off-by: Hou Tao Signed-off-by: Daniel Borkmann Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20231216035510.4030605-1-houtao@huaweicloud.com --- tools/testing/selftests/bpf/progs/normal_map_btf.c | 56 ++++++++++++++++++++++ 1 file changed, 56 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/normal_map_btf.c (limited to 'tools/testing/selftests/bpf/progs/normal_map_btf.c') diff --git a/tools/testing/selftests/bpf/progs/normal_map_btf.c b/tools/testing/selftests/bpf/progs/normal_map_btf.c new file mode 100644 index 000000000000..66cde82aa86d --- /dev/null +++ b/tools/testing/selftests/bpf/progs/normal_map_btf.c @@ -0,0 +1,56 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2023. Huawei Technologies Co., Ltd */ +#include +#include +#include + +#include "bpf_misc.h" +#include "bpf_experimental.h" + +struct node_data { + __u64 data; + struct bpf_list_node node; +}; + +struct map_value { + struct bpf_list_head head __contains(node_data, node); + struct bpf_spin_lock lock; +}; + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY); + __type(key, int); + __type(value, struct map_value); + __uint(max_entries, 1); +} array SEC(".maps"); + +char _license[] SEC("license") = "GPL"; + +int pid = 0; +bool done = false; + +SEC("fentry/" SYS_PREFIX "sys_nanosleep") +int add_to_list_in_array(void *ctx) +{ + struct map_value *value; + struct node_data *new; + int zero = 0; + + if (done || (u32)bpf_get_current_pid_tgid() != pid) + return 0; + + value = bpf_map_lookup_elem(&array, &zero); + if (!value) + return 0; + + new = bpf_obj_new(typeof(*new)); + if (!new) + return 0; + + bpf_spin_lock(&value->lock); + bpf_list_push_back(&value->head, &new->node); + bpf_spin_unlock(&value->lock); + done = true; + + return 0; +} -- cgit