From 1624918be84a8bcc4f592e55635bc4fe4a96460a Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Mon, 4 Dec 2023 22:04:24 +0800 Subject: selftests/bpf: Add test cases for inner map Add test cases to test the race between the destroy of inner map due to map-in-map update and the access of inner map in bpf program. The following 4 combinations are added: (1) array map in map array + bpf program (2) array map in map array + sleepable bpf program (3) array map in map htab + bpf program (4) array map in map htab + sleepable bpf program Before applying the fixes, when running `./test_prog -a map_in_map`, the following error was reported: ================================================================== BUG: KASAN: slab-use-after-free in array_map_update_elem+0x48/0x3e0 Read of size 4 at addr ffff888114f33824 by task test_progs/1858 CPU: 1 PID: 1858 Comm: test_progs Tainted: G O 6.6.0+ #7 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996) ...... Call Trace: dump_stack_lvl+0x4a/0x90 print_report+0xd2/0x620 kasan_report+0xd1/0x110 __asan_load4+0x81/0xa0 array_map_update_elem+0x48/0x3e0 bpf_prog_be94a9f26772f5b7_access_map_in_array+0xe6/0xf6 trace_call_bpf+0x1aa/0x580 kprobe_perf_func+0xdd/0x430 kprobe_dispatcher+0xa0/0xb0 kprobe_ftrace_handler+0x18b/0x2e0 0xffffffffc02280f7 RIP: 0010:__x64_sys_getpgid+0x1/0x30 ...... Allocated by task 1857: kasan_save_stack+0x26/0x50 kasan_set_track+0x25/0x40 kasan_save_alloc_info+0x1e/0x30 __kasan_kmalloc+0x98/0xa0 __kmalloc_node+0x6a/0x150 __bpf_map_area_alloc+0x141/0x170 bpf_map_area_alloc+0x10/0x20 array_map_alloc+0x11f/0x310 map_create+0x28a/0xb40 __sys_bpf+0x753/0x37c0 __x64_sys_bpf+0x44/0x60 do_syscall_64+0x36/0xb0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 Freed by task 11: kasan_save_stack+0x26/0x50 kasan_set_track+0x25/0x40 kasan_save_free_info+0x2b/0x50 __kasan_slab_free+0x113/0x190 slab_free_freelist_hook+0xd7/0x1e0 __kmem_cache_free+0x170/0x260 kfree+0x9b/0x160 kvfree+0x2d/0x40 bpf_map_area_free+0xe/0x20 array_map_free+0x120/0x2c0 bpf_map_free_deferred+0xd7/0x1e0 process_one_work+0x462/0x990 worker_thread+0x370/0x670 kthread+0x1b0/0x200 ret_from_fork+0x3a/0x70 ret_from_fork_asm+0x1b/0x30 Last potentially related work creation: kasan_save_stack+0x26/0x50 __kasan_record_aux_stack+0x94/0xb0 kasan_record_aux_stack_noalloc+0xb/0x20 __queue_work+0x331/0x950 queue_work_on+0x75/0x80 bpf_map_put+0xfa/0x160 bpf_map_fd_put_ptr+0xe/0x20 bpf_fd_array_map_update_elem+0x174/0x1b0 bpf_map_update_value+0x2b7/0x4a0 __sys_bpf+0x2551/0x37c0 __x64_sys_bpf+0x44/0x60 do_syscall_64+0x36/0xb0 entry_SYSCALL_64_after_hwframe+0x6e/0x76 Signed-off-by: Hou Tao Link: https://lore.kernel.org/r/20231204140425.1480317-7-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- .../selftests/bpf/progs/access_map_in_map.c | 93 ++++++++++++++++++++++ 1 file changed, 93 insertions(+) create mode 100644 tools/testing/selftests/bpf/progs/access_map_in_map.c (limited to 'tools/testing/selftests/bpf/progs/access_map_in_map.c') diff --git a/tools/testing/selftests/bpf/progs/access_map_in_map.c b/tools/testing/selftests/bpf/progs/access_map_in_map.c new file mode 100644 index 000000000000..1126871c2ebd --- /dev/null +++ b/tools/testing/selftests/bpf/progs/access_map_in_map.c @@ -0,0 +1,93 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2023. Huawei Technologies Co., Ltd */ +#include +#include +#include + +#include "bpf_misc.h" + +struct inner_map_type { + __uint(type, BPF_MAP_TYPE_ARRAY); + __uint(key_size, 4); + __uint(value_size, 4); + __uint(max_entries, 1); +} inner_map SEC(".maps"); + +struct { + __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS); + __type(key, int); + __type(value, int); + __uint(max_entries, 1); + __array(values, struct inner_map_type); +} outer_array_map SEC(".maps") = { + .values = { + [0] = &inner_map, + }, +}; + +struct { + __uint(type, BPF_MAP_TYPE_HASH_OF_MAPS); + __type(key, int); + __type(value, int); + __uint(max_entries, 1); + __array(values, struct inner_map_type); +} outer_htab_map SEC(".maps") = { + .values = { + [0] = &inner_map, + }, +}; + +char _license[] SEC("license") = "GPL"; + +int tgid = 0; + +static int acc_map_in_map(void *outer_map) +{ + int i, key, value = 0xdeadbeef; + void *inner_map; + + if ((bpf_get_current_pid_tgid() >> 32) != tgid) + return 0; + + /* Find nonexistent inner map */ + key = 1; + inner_map = bpf_map_lookup_elem(outer_map, &key); + if (inner_map) + return 0; + + /* Find the old inner map */ + key = 0; + inner_map = bpf_map_lookup_elem(outer_map, &key); + if (!inner_map) + return 0; + + /* Wait for the old inner map to be replaced */ + for (i = 0; i < 2048; i++) + bpf_map_update_elem(inner_map, &key, &value, 0); + + return 0; +} + +SEC("?kprobe/" SYS_PREFIX "sys_getpgid") +int access_map_in_array(void *ctx) +{ + return acc_map_in_map(&outer_array_map); +} + +SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") +int sleepable_access_map_in_array(void *ctx) +{ + return acc_map_in_map(&outer_array_map); +} + +SEC("?kprobe/" SYS_PREFIX "sys_getpgid") +int access_map_in_htab(void *ctx) +{ + return acc_map_in_map(&outer_htab_map); +} + +SEC("?fentry.s/" SYS_PREFIX "sys_getpgid") +int sleepable_access_map_in_htab(void *ctx) +{ + return acc_map_in_map(&outer_htab_map); +} -- cgit