From de7b9927105bd2afe940c6ad22de6938edd8b1c1 Mon Sep 17 00:00:00 2001 From: Kumar Kartikeya Dwivedi Date: Tue, 9 Aug 2022 23:30:33 +0200 Subject: selftests/bpf: Add test for prealloc_lru_pop bug Add a regression test to check against invalid check_and_init_map_value call inside prealloc_lru_pop. The kptr should not be reset to NULL once we set it after deleting the map element. Hence, we trigger a program that updates the element causing its reuse, and checks whether the unref kptr is reset or not. If it is, prealloc_lru_pop does an incorrect check_and_init_map_value call and the test fails. Acked-by: Yonghong Song Signed-off-by: Kumar Kartikeya Dwivedi Link: https://lore.kernel.org/r/20220809213033.24147-4-memxor@gmail.com Signed-off-by: Alexei Starovoitov --- tools/testing/selftests/bpf/prog_tests/lru_bug.c | 21 ++++++++++ tools/testing/selftests/bpf/progs/lru_bug.c | 49 ++++++++++++++++++++++++ 2 files changed, 70 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/lru_bug.c create mode 100644 tools/testing/selftests/bpf/progs/lru_bug.c (limited to 'tools/testing') diff --git a/tools/testing/selftests/bpf/prog_tests/lru_bug.c b/tools/testing/selftests/bpf/prog_tests/lru_bug.c new file mode 100644 index 000000000000..3c7822390827 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/lru_bug.c @@ -0,0 +1,21 @@ +// SPDX-License-Identifier: GPL-2.0 +#include + +#include "lru_bug.skel.h" + +void test_lru_bug(void) +{ + struct lru_bug *skel; + int ret; + + skel = lru_bug__open_and_load(); + if (!ASSERT_OK_PTR(skel, "lru_bug__open_and_load")) + return; + ret = lru_bug__attach(skel); + if (!ASSERT_OK(ret, "lru_bug__attach")) + goto end; + usleep(1); + ASSERT_OK(skel->data->result, "prealloc_lru_pop doesn't call check_and_init_map_value"); +end: + lru_bug__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/lru_bug.c b/tools/testing/selftests/bpf/progs/lru_bug.c new file mode 100644 index 000000000000..687081a724b3 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/lru_bug.c @@ -0,0 +1,49 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include +#include + +struct map_value { + struct task_struct __kptr *ptr; +}; + +struct { + __uint(type, BPF_MAP_TYPE_LRU_HASH); + __uint(max_entries, 1); + __type(key, int); + __type(value, struct map_value); +} lru_map SEC(".maps"); + +int pid = 0; +int result = 1; + +SEC("fentry/bpf_ktime_get_ns") +int printk(void *ctx) +{ + struct map_value v = {}; + + if (pid == bpf_get_current_task_btf()->pid) + bpf_map_update_elem(&lru_map, &(int){0}, &v, 0); + return 0; +} + +SEC("fentry/do_nanosleep") +int nanosleep(void *ctx) +{ + struct map_value val = {}, *v; + struct task_struct *current; + + bpf_map_update_elem(&lru_map, &(int){0}, &val, 0); + v = bpf_map_lookup_elem(&lru_map, &(int){0}); + if (!v) + return 0; + bpf_map_delete_elem(&lru_map, &(int){0}); + current = bpf_get_current_task_btf(); + v->ptr = current; + pid = current->pid; + bpf_ktime_get_ns(); + result = !v->ptr; + return 0; +} + +char _license[] SEC("license") = "GPL"; -- cgit v1.2.3