From 797d73ee232dd1833dec4824bc53a22032e97c1c Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Tue, 8 Oct 2024 15:11:13 +0800 Subject: [PATCH 1/2] bpf: Check the remaining info_cnt before repeating btf fields When trying to repeat the btf fields for array of nested struct, it doesn't check the remaining info_cnt. The following splat will be reported when the value of ret * nelems is greater than BTF_FIELDS_MAX: ------------[ cut here ]------------ UBSAN: array-index-out-of-bounds in ../kernel/bpf/btf.c:3951:49 index 11 is out of range for type 'btf_field_info [11]' CPU: 6 UID: 0 PID: 411 Comm: test_progs ...... 6.11.0-rc4+ #1 Tainted: [O]=OOT_MODULE Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS ... Call Trace: dump_stack_lvl+0x57/0x70 dump_stack+0x10/0x20 ubsan_epilogue+0x9/0x40 __ubsan_handle_out_of_bounds+0x6f/0x80 ? kallsyms_lookup_name+0x48/0xb0 btf_parse_fields+0x992/0xce0 map_create+0x591/0x770 __sys_bpf+0x229/0x2410 __x64_sys_bpf+0x1f/0x30 x64_sys_call+0x199/0x9f0 do_syscall_64+0x3b/0xc0 entry_SYSCALL_64_after_hwframe+0x4b/0x53 RIP: 0033:0x7fea56f2cc5d ...... ---[ end trace ]--- Fix it by checking the remaining info_cnt in btf_repeat_fields() before repeating the btf fields. Fixes: 64e8ee814819 ("bpf: look into the types of the fields of a struct type recursively.") Signed-off-by: Hou Tao Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20241008071114.3718177-2-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- kernel/bpf/btf.c | 14 ++++++++++---- 1 file changed, 10 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c index a05da5f4354742..5cd1c7a23848cc 100644 --- a/kernel/bpf/btf.c +++ b/kernel/bpf/btf.c @@ -3523,7 +3523,7 @@ static int btf_get_field_type(const struct btf *btf, const struct btf_type *var_ * (i + 1) * elem_size * where i is the repeat index and elem_size is the size of an element. */ -static int btf_repeat_fields(struct btf_field_info *info, +static int btf_repeat_fields(struct btf_field_info *info, int info_cnt, u32 field_cnt, u32 repeat_cnt, u32 elem_size) { u32 i, j; @@ -3543,6 +3543,12 @@ static int btf_repeat_fields(struct btf_field_info *info, } } + /* The type of struct size or variable size is u32, + * so the multiplication will not overflow. + */ + if (field_cnt * (repeat_cnt + 1) > info_cnt) + return -E2BIG; + cur = field_cnt; for (i = 0; i < repeat_cnt; i++) { memcpy(&info[cur], &info[0], field_cnt * sizeof(info[0])); @@ -3587,7 +3593,7 @@ static int btf_find_nested_struct(const struct btf *btf, const struct btf_type * info[i].off += off; if (nelems > 1) { - err = btf_repeat_fields(info, ret, nelems - 1, t->size); + err = btf_repeat_fields(info, info_cnt, ret, nelems - 1, t->size); if (err == 0) ret *= nelems; else @@ -3681,10 +3687,10 @@ static int btf_find_field_one(const struct btf *btf, if (ret == BTF_FIELD_IGNORE) return 0; - if (nelems > info_cnt) + if (!info_cnt) return -E2BIG; if (nelems > 1) { - ret = btf_repeat_fields(info, 1, nelems - 1, sz); + ret = btf_repeat_fields(info, info_cnt, 1, nelems - 1, sz); if (ret < 0) return ret; } From c456f08040589a5096481277c83168a4e7ae7ed7 Mon Sep 17 00:00:00 2001 From: Hou Tao Date: Tue, 8 Oct 2024 15:11:14 +0800 Subject: [PATCH 2/2] selftests/bpf: Add more test case for field flattening Add three success test cases to test the flattening of array of nested struct. For these three tests, the number of special fields in map is BTF_FIELDS_MAX, but the array is defined in structs with different nested level. Add one failure test case for the flattening as well. In the test case, the number of special fields in map is BTF_FIELDS_MAX + 1. It will make btf_parse_fields() in map_create() return -E2BIG, the creation of map will succeed, but the load of program will fail because the btf_record is invalid for the map. Signed-off-by: Hou Tao Acked-by: Eduard Zingerman Link: https://lore.kernel.org/r/20241008071114.3718177-3-houtao@huaweicloud.com Signed-off-by: Alexei Starovoitov --- .../selftests/bpf/prog_tests/cpumask.c | 1 + .../selftests/bpf/progs/cpumask_common.h | 5 ++ .../selftests/bpf/progs/cpumask_failure.c | 35 +++++++++ .../selftests/bpf/progs/cpumask_success.c | 78 ++++++++++++++++++- 4 files changed, 117 insertions(+), 2 deletions(-) diff --git a/tools/testing/selftests/bpf/prog_tests/cpumask.c b/tools/testing/selftests/bpf/prog_tests/cpumask.c index 2570bd4b0cb228..e58a04654238c9 100644 --- a/tools/testing/selftests/bpf/prog_tests/cpumask.c +++ b/tools/testing/selftests/bpf/prog_tests/cpumask.c @@ -23,6 +23,7 @@ static const char * const cpumask_success_testcases[] = { "test_global_mask_array_l2_rcu", "test_global_mask_nested_rcu", "test_global_mask_nested_deep_rcu", + "test_global_mask_nested_deep_array_rcu", "test_cpumask_weight", }; diff --git a/tools/testing/selftests/bpf/progs/cpumask_common.h b/tools/testing/selftests/bpf/progs/cpumask_common.h index b979e91f55f079..4ece7873ba609d 100644 --- a/tools/testing/selftests/bpf/progs/cpumask_common.h +++ b/tools/testing/selftests/bpf/progs/cpumask_common.h @@ -7,6 +7,11 @@ #include "errno.h" #include +/* Should use BTF_FIELDS_MAX, but it is not always available in vmlinux.h, + * so use the hard-coded number as a workaround. + */ +#define CPUMASK_KPTR_FIELDS_MAX 11 + int err; #define private(name) SEC(".bss." #name) __attribute__((aligned(8))) diff --git a/tools/testing/selftests/bpf/progs/cpumask_failure.c b/tools/testing/selftests/bpf/progs/cpumask_failure.c index a988d2823b5285..b40b52548ffb0e 100644 --- a/tools/testing/selftests/bpf/progs/cpumask_failure.c +++ b/tools/testing/selftests/bpf/progs/cpumask_failure.c @@ -10,6 +10,21 @@ char _license[] SEC("license") = "GPL"; +struct kptr_nested_array_2 { + struct bpf_cpumask __kptr * mask; +}; + +struct kptr_nested_array_1 { + /* Make btf_parse_fields() in map_create() return -E2BIG */ + struct kptr_nested_array_2 d_2[CPUMASK_KPTR_FIELDS_MAX + 1]; +}; + +struct kptr_nested_array { + struct kptr_nested_array_1 d_1; +}; + +private(MASK_NESTED) static struct kptr_nested_array global_mask_nested_arr; + /* Prototype for all of the program trace events below: * * TRACE_EVENT(task_newtask, @@ -187,3 +202,23 @@ int BPF_PROG(test_global_mask_rcu_no_null_check, struct task_struct *task, u64 c return 0; } + +SEC("tp_btf/task_newtask") +__failure __msg("has no valid kptr") +int BPF_PROG(test_invalid_nested_array, struct task_struct *task, u64 clone_flags) +{ + struct bpf_cpumask *local, *prev; + + local = create_cpumask(); + if (!local) + return 0; + + prev = bpf_kptr_xchg(&global_mask_nested_arr.d_1.d_2[CPUMASK_KPTR_FIELDS_MAX].mask, local); + if (prev) { + bpf_cpumask_release(prev); + err = 3; + return 0; + } + + return 0; +} diff --git a/tools/testing/selftests/bpf/progs/cpumask_success.c b/tools/testing/selftests/bpf/progs/cpumask_success.c index fd8106831c32c3..80ee469b0b6028 100644 --- a/tools/testing/selftests/bpf/progs/cpumask_success.c +++ b/tools/testing/selftests/bpf/progs/cpumask_success.c @@ -31,11 +31,59 @@ struct kptr_nested_deep { struct kptr_nested_pair ptr_pairs[3]; }; +struct kptr_nested_deep_array_1_2 { + int dummy; + struct bpf_cpumask __kptr * mask[CPUMASK_KPTR_FIELDS_MAX]; +}; + +struct kptr_nested_deep_array_1_1 { + int dummy; + struct kptr_nested_deep_array_1_2 d_2; +}; + +struct kptr_nested_deep_array_1 { + long dummy; + struct kptr_nested_deep_array_1_1 d_1; +}; + +struct kptr_nested_deep_array_2_2 { + long dummy[2]; + struct bpf_cpumask __kptr * mask; +}; + +struct kptr_nested_deep_array_2_1 { + int dummy; + struct kptr_nested_deep_array_2_2 d_2[CPUMASK_KPTR_FIELDS_MAX]; +}; + +struct kptr_nested_deep_array_2 { + long dummy; + struct kptr_nested_deep_array_2_1 d_1; +}; + +struct kptr_nested_deep_array_3_2 { + long dummy[2]; + struct bpf_cpumask __kptr * mask; +}; + +struct kptr_nested_deep_array_3_1 { + int dummy; + struct kptr_nested_deep_array_3_2 d_2; +}; + +struct kptr_nested_deep_array_3 { + long dummy; + struct kptr_nested_deep_array_3_1 d_1[CPUMASK_KPTR_FIELDS_MAX]; +}; + private(MASK) static struct bpf_cpumask __kptr * global_mask_array[2]; private(MASK) static struct bpf_cpumask __kptr * global_mask_array_l2[2][1]; private(MASK) static struct bpf_cpumask __kptr * global_mask_array_one[1]; private(MASK) static struct kptr_nested global_mask_nested[2]; private(MASK_DEEP) static struct kptr_nested_deep global_mask_nested_deep; +private(MASK_1) static struct kptr_nested_deep_array_1 global_mask_nested_deep_array_1; +private(MASK_2) static struct kptr_nested_deep_array_2 global_mask_nested_deep_array_2; +private(MASK_3) static struct kptr_nested_deep_array_3 global_mask_nested_deep_array_3; static bool is_test_task(void) { @@ -543,12 +591,21 @@ static int _global_mask_array_rcu(struct bpf_cpumask **mask0, goto err_exit; } - /* [, NULL] */ - if (!*mask0 || *mask1) { + /* [, *] */ + if (!*mask0) { err = 2; goto err_exit; } + if (!mask1) + goto err_exit; + + /* [*, NULL] */ + if (*mask1) { + err = 3; + goto err_exit; + } + local = create_cpumask(); if (!local) { err = 9; @@ -631,6 +688,23 @@ int BPF_PROG(test_global_mask_nested_deep_rcu, struct task_struct *task, u64 clo return 0; } +SEC("tp_btf/task_newtask") +int BPF_PROG(test_global_mask_nested_deep_array_rcu, struct task_struct *task, u64 clone_flags) +{ + int i; + + for (i = 0; i < CPUMASK_KPTR_FIELDS_MAX; i++) + _global_mask_array_rcu(&global_mask_nested_deep_array_1.d_1.d_2.mask[i], NULL); + + for (i = 0; i < CPUMASK_KPTR_FIELDS_MAX; i++) + _global_mask_array_rcu(&global_mask_nested_deep_array_2.d_1.d_2[i].mask, NULL); + + for (i = 0; i < CPUMASK_KPTR_FIELDS_MAX; i++) + _global_mask_array_rcu(&global_mask_nested_deep_array_3.d_1[i].d_2.mask, NULL); + + return 0; +} + SEC("tp_btf/task_newtask") int BPF_PROG(test_cpumask_weight, struct task_struct *task, u64 clone_flags) {