6.9-stable review patch. If anyone has any objections, please let me know.
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From: Eduard Zingerman eddyz87@gmail.com
[ Upstream commit 980ca8ceeae69ddf362870ea9183f389ae26324a ]
When doing BPF_PROG_TEST_RUN for bpf_dummy_struct_ops programs, reject execution when NULL is passed for non-nullable params. For programs with non-nullable params verifier assumes that such params are never NULL and thus might optimize out NULL checks.
Suggested-by: Kui-Feng Lee sinquersw@gmail.com Signed-off-by: Eduard Zingerman eddyz87@gmail.com Link: https://lore.kernel.org/r/20240424012821.595216-5-eddyz87@gmail.com Signed-off-by: Alexei Starovoitov ast@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/bpf/bpf_dummy_struct_ops.c | 51 +++++++++++++++++++++++++++++++++- 1 file changed, 50 insertions(+), 1 deletion(-)
diff --git a/net/bpf/bpf_dummy_struct_ops.c b/net/bpf/bpf_dummy_struct_ops.c index fdbe30ad8db2f..7236349cf0598 100644 --- a/net/bpf/bpf_dummy_struct_ops.c +++ b/net/bpf/bpf_dummy_struct_ops.c @@ -79,6 +79,51 @@ static int dummy_ops_call_op(void *image, struct bpf_dummy_ops_test_args *args) args->args[3], args->args[4]); }
+static const struct bpf_ctx_arg_aux *find_ctx_arg_info(struct bpf_prog_aux *aux, int offset) +{ + int i; + + for (i = 0; i < aux->ctx_arg_info_size; i++) + if (aux->ctx_arg_info[i].offset == offset) + return &aux->ctx_arg_info[i]; + + return NULL; +} + +/* There is only one check at the moment: + * - zero should not be passed for pointer parameters not marked as nullable. + */ +static int check_test_run_args(struct bpf_prog *prog, struct bpf_dummy_ops_test_args *args) +{ + const struct btf_type *func_proto = prog->aux->attach_func_proto; + + for (u32 arg_no = 0; arg_no < btf_type_vlen(func_proto) ; ++arg_no) { + const struct btf_param *param = &btf_params(func_proto)[arg_no]; + const struct bpf_ctx_arg_aux *info; + const struct btf_type *t; + int offset; + + if (args->args[arg_no] != 0) + continue; + + /* Program is validated already, so there is no need + * to check if t is NULL. + */ + t = btf_type_skip_modifiers(bpf_dummy_ops_btf, param->type, NULL); + if (!btf_type_is_ptr(t)) + continue; + + offset = btf_ctx_arg_offset(bpf_dummy_ops_btf, func_proto, arg_no); + info = find_ctx_arg_info(prog->aux, offset); + if (info && (info->reg_type & PTR_MAYBE_NULL)) + continue; + + return -EINVAL; + } + + return 0; +} + extern const struct bpf_link_ops bpf_struct_ops_link_lops;
int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr, @@ -87,7 +132,7 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr, const struct bpf_struct_ops *st_ops = &bpf_bpf_dummy_ops; const struct btf_type *func_proto; struct bpf_dummy_ops_test_args *args; - struct bpf_tramp_links *tlinks; + struct bpf_tramp_links *tlinks = NULL; struct bpf_tramp_link *link = NULL; void *image = NULL; unsigned int op_idx; @@ -109,6 +154,10 @@ int bpf_struct_ops_test_run(struct bpf_prog *prog, const union bpf_attr *kattr, if (IS_ERR(args)) return PTR_ERR(args);
+ err = check_test_run_args(prog, args); + if (err) + goto out; + tlinks = kcalloc(BPF_TRAMP_MAX, sizeof(*tlinks), GFP_KERNEL); if (!tlinks) { err = -ENOMEM;