From: Dave Marchevsky <davemarchevsky@fb.com>
Date: Mon, 3 Apr 2023 13:00:27 -0700
Subject: [PATCH] bpf: Fix struct_meta lookup for bpf_obj_free_fields kfunc
call
References: bsc#1012628
Patch-mainline: 6.3.2
Git-commit: f6a6a5a976288e4d0d94eb1c6c9e983e8e5cdb31
[ Upstream commit f6a6a5a976288e4d0d94eb1c6c9e983e8e5cdb31 ]
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
kernel/bpf/verifier.c | 14 +++++++++-----
1 file changed, 9 insertions(+), 5 deletions(-)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 559c9137..64600acb 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -10002,10 +10002,6 @@ 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;
@@ -10090,7 +10086,15 @@ 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);
--
2.35.3