diff options
| author | Dave Marchevsky <davemarchevsky@fb.com> | 2023-04-03 13:00:27 -0700 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2023-04-03 14:54:21 -0700 |
| commit | f6a6a5a976288e4d0d94eb1c6c9e983e8e5cdb31 (patch) | |
| tree | 3be308f941dc363907dec50b22542c7a0da09457 /kernel | |
| parent | 16b7c970cc8192e929dbd5192ccc1867e19d7bda (diff) | |
bpf: Fix struct_meta lookup for bpf_obj_free_fields kfunc call
bpf_obj_drop_impl has a void return type. In check_kfunc_call, the "else
if" which sets insn_aux->kptr_struct_meta for bpf_obj_drop_impl is
surrounded by a larger if statement which checks btf_type_is_ptr. As a
result:
* The bpf_obj_drop_impl-specific code will never execute
* The btf_struct_meta input to bpf_obj_drop is always NULL
* __bpf_obj_drop_impl will always see a NULL btf_record when called
from BPF program, and won't call bpf_obj_free_fields
* program-allocated kptrs which have fields that should be cleaned up
by bpf_obj_free_fields may instead leak resources
This patch adds a btf_type_is_void branch to the larger if and moves
special handling for bpf_obj_drop_impl there, fixing the issue.
Fixes: ac9f06050a35 ("bpf: Introduce bpf_obj_drop")
Cc: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Link: https://lore.kernel.org/r/20230403200027.2271029-1-davemarchevsky@fb.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 92ae4e8ab87b..eaf9c5291cf0 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -10743,10 +10743,6 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, insn_aux->obj_new_size = ret_t->size; insn_aux->kptr_struct_meta = btf_find_struct_meta(ret_btf, ret_btf_id); - } else if (meta.func_id == special_kfunc_list[KF_bpf_obj_drop_impl]) { - insn_aux->kptr_struct_meta = - btf_find_struct_meta(meta.arg_obj_drop.btf, - meta.arg_obj_drop.btf_id); } else if (meta.func_id == special_kfunc_list[KF_bpf_list_pop_front] || meta.func_id == special_kfunc_list[KF_bpf_list_pop_back]) { struct btf_field *field = meta.arg_list_head.field; @@ -10875,7 +10871,15 @@ static int check_kfunc_call(struct bpf_verifier_env *env, struct bpf_insn *insn, if (reg_may_point_to_spin_lock(®s[BPF_REG_0]) && !regs[BPF_REG_0].id) regs[BPF_REG_0].id = ++env->id_gen; - } /* else { add_kfunc_call() ensures it is btf_type_is_void(t) } */ + } else if (btf_type_is_void(t)) { + if (meta.btf == btf_vmlinux && btf_id_set_contains(&special_kfunc_set, meta.func_id)) { + if (meta.func_id == special_kfunc_list[KF_bpf_obj_drop_impl]) { + insn_aux->kptr_struct_meta = + btf_find_struct_meta(meta.arg_obj_drop.btf, + meta.arg_obj_drop.btf_id); + } + } + } nargs = btf_type_vlen(meta.func_proto); args = (const struct btf_param *)(meta.func_proto + 1); |