[PATCH AUTOSEL 5.15 32/46] bpf: Prevent decl_tag from being referenced in func_proto arg

Sasha Levin
2022-12-18T16:42:52Z

From: Stanislav Fomichev <sdf@google.com>

[ Upstream commit f17472d4599697d701aa239b4c475a506bccfd19 ]

Syzkaller managed to hit another decl_tag issue:

btf_func_proto_check kernel/bpf/btf.c:4506 [inline]
btf_check_all_types kernel/bpf/btf.c:4734 [inline]
btf_parse_type_sec+0x1175/0x1980 kernel/bpf/btf.c:4763
btf_parse kernel/bpf/btf.c:5042 [inline]
btf_new_fd+0x65a/0xb00 kernel/bpf/btf.c:6709
bpf_btf_load+0x6f/0x90 kernel/bpf/syscall.c:4342
__sys_bpf+0x50a/0x6c0 kernel/bpf/syscall.c:5034
__do_sys_bpf kernel/bpf/syscall.c:5093 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5091 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5091
do_syscall_64+0x54/0x70 arch/x86/entry/common.c:48

This seems similar to commit ea68376c8bed ("bpf: prevent decl_tag from being
referenced in func_proto") but for the argument.

Reported-by: syzbot+8dd0551dda6020944c5d@syzkaller.appspotmail.com
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20221123035422.872531-2-sdf@google.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
kernel/bpf/btf.c | 5 +++++
1 file changed, 5 insertions(+)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 7cb13b9f69a6..0c2fa93bd8d2 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -3864,6 +3864,11 @@ static int btf_func_proto_check(struct btf_verifier_env *env,
break;
}

+ if (btf_type_is_resolve_source_only(arg_type)) {
+ btf_verifier_log_type(env, t, "Invalid arg#%u", i + 1);
+ return -EINVAL;
+ }
+
if (args[i].name_off &&
(!btf_name_offset_valid(btf, args[i].name_off) ||
!btf_name_valid_identifier(btf, args[i].name_off))) {
--
2.35.1