linux-kernel - [PATCH AUTOSEL 5.4 22/30] bpf: Prevent decl_tag from being referenced in func

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Date:   Sun, 18 Dec 2022 11:18:27 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Stanislav Fomichev <sdf@...gle.com>,
        syzbot+8dd0551dda6020944c5d@...kaller.appspotmail.com,
        Daniel Borkmann <daniel@...earbox.net>,
        Yonghong Song <yhs@...com>, Sasha Levin <sashal@...nel.org>,
        martin.lau@...ux.dev, ast@...nel.org, andrii@...nel.org,
        bpf@...r.kernel.org
Subject: [PATCH AUTOSEL 5.4 22/30] bpf: Prevent decl_tag from being referenced in func_proto arg

From: Stanislav Fomichev <sdf@...gle.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@...kaller.appspotmail.com
Signed-off-by: Stanislav Fomichev <sdf@...gle.com>
Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
Acked-by: Yonghong Song <yhs@...com>
Link: https://lore.kernel.org/bpf/20221123035422.872531-2-sdf@google.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 kernel/bpf/btf.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index a28bbec8c59f..8fd65a0eb7f3 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -2849,6 +2849,11 @@ 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