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    Subject[PATCH AUTOSEL 6.0 48/73] bpf: Prevent decl_tag from being referenced in func_proto arg
    Date
    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 0d23d4bcd81c..44e93c3abebd 100644
    --- a/kernel/bpf/btf.c
    +++ b/kernel/bpf/btf.c
    @@ -4481,6 +4481,11 @@ 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
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