From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-36.mta1.migadu.com [95.215.58.36]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B34D93B14B8 for ; Mon, 31 Aug 2026 11:05:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.36 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788174324; cv=none; b=iKG7QzJ5Dg5aluZPjtDucj9vubPVDlA9LZ8X98/Oj7cc3L8bxGFhEY8nGEBStgV3lds5NGQhz0ZkIke4UPuTHyY/1OXTdMjNAZHIQTTObEW16fQSIxPa/F7vlGh11GEOhhhvnRU9dATFXO7BzUqUSD8lNjoo8AB08tr9cDWhQ4s= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788174324; c=relaxed/simple; bh=8WHtN6ourocR0E48NCxNPrEIJOFHpFqlFquB2qhCgpA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Dzqn1YMpqghnvPBWVT+XcvOq62zZnK0O3U2be28arLjvrSemaLsVnHQlb+ta7tHhrJfFdMVaCZGFvm2NX8Vz59YBlLIALpYMmezKxWc/2IpB7fjfTNu+uEkavcWx1lRrm5vqQPGrZlFxGg3a7siX64c5jGRxr5nJAsRqcmSTFgM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=mRV5w/Sq; arc=none smtp.client-ip=95.215.58.36 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="mRV5w/Sq" X-Envelope-To: bpf@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=8WHtN6ourocR0E48NCxNPrEIJOFHpFqlFquB2qhCgpA=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1788174320; v=1; x=1788779120; b=mRV5w/SqUAWJ2quLPiAcMmP0XSiUMu7x1cbKU0KXKv9Y+XF6CC9QLaAhJRNAz4+7zK0pYBZY 7x0dOeXYA0OC9r2bpSstmlrZXREGT7xnPSGMVzF7ZfkVH/jIic3yqv7ZomWKQqo1FxFtBLuaOce euavRX1TxVLFwXYLfs16CAH8= X-Envelope-To: bpf@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id 97a19a524f8c428b; Mon, 31 Aug 2026 11:05:20 +0000 X-Mizu-Trace-ID: 97a19a524f8c428b X-Migadu-Flow: FLOW_OUT From: Jiayuan Chen To: bpf@vger.kernel.org Cc: Jiayuan Chen , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Kumar Kartikeya Dwivedi , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Ihor Solodrai , Shuah Khan , Mykyta Yatsenko , Alan Maguire , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf v3 4/5] selftests/bpf: Add test for key-less BTF hash map Date: Mon, 31 Aug 2026 19:01:09 +0800 Message-ID: <20260831110314.150870-5-jiayuan.chen@linux.dev> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260831110314.150870-1-jiayuan.chen@linux.dev> References: <20260831110314.150870-1-jiayuan.chen@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Create a hash and an rhash map with btf_key_type_id == 0 and expect bpf_map_create() to fail with -EINVAL; a positive control with a real key type confirms the rejection is about the key-less BTF. On an unfixed kernel the map is created, and the test pins and reads it back to walk the bpffs dump path, which reproduces the btf_type_show() NULL-deref - so running it on an unfixed kernel oopses the reading task (and panics it under panic_on_oops). Signed-off-by: Jiayuan Chen --- .../bpf/prog_tests/btf_map_keyless.c | 82 +++++++++++++++++++ 1 file changed, 82 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/btf_map_keyless.c diff --git a/tools/testing/selftests/bpf/prog_tests/btf_map_keyless.c b/tools/testing/selftests/bpf/prog_tests/btf_map_keyless.c new file mode 100644 index 000000000000..a7d037f57a7e --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/btf_map_keyless.c @@ -0,0 +1,82 @@ +// SPDX-License-Identifier: GPL-2.0 +#include +#include + +/* + * A hash map with a key-less BTF (btf_key_type_id == 0) used to NULL-deref in + * btf_type_show() when dumped via bpffs. + * A fixed kernel rejects such a map at creation; on an unfixed kernel the + * pin-and-read below deliberately walks that bpffs dump path, so it doubles + * as a reproducer: it oopses an unfixed kernel (and panics it under + * panic_on_oops). + */ +static void check_keyless(int map_type, __u32 map_flags, int btf_fd, int val_id) +{ + LIBBPF_OPTS(bpf_map_create_opts, opts); + const char *path = "/sys/fs/bpf/keyless_map"; + __u32 key = 1, val = 0x41424344; + char buf[256]; + int map_fd; + FILE *f; + + opts.map_flags = map_flags; + opts.btf_fd = btf_fd; + opts.btf_value_type_id = val_id; + + /* + * Positive control: the same map with a real key type must be accepted, + * so the -EINVAL below is about the key-less BTF and not some unrelated + * rejection (e.g. an unknown map type). + */ + opts.btf_key_type_id = val_id; + map_fd = bpf_map_create(map_type, "keyed_map", 4, 4, 8, &opts); + if (!ASSERT_GE(map_fd, 0, "keyed create is accepted")) + return; + close(map_fd); + + /* A key-less BTF must be rejected. */ + opts.btf_key_type_id = 0; + map_fd = bpf_map_create(map_type, "keyless_map", 4, 4, 8, &opts); + + if (map_fd >= 0) { + /* Unfixed kernel: reproduce the oops via the bpffs dump path. */ + (void)bpf_map_update_elem(map_fd, &key, &val, 0); + if (bpf_obj_pin(map_fd, path) == 0) { + f = fopen(path, "r"); + if (f) { + while (fgets(buf, sizeof(buf), f)) + ; + fclose(f); + } + unlink(path); + } + close(map_fd); + } + + ASSERT_EQ(map_fd, -EINVAL, "key-less create is rejected"); +} + +void test_btf_map_keyless(void) +{ + int btf_fd, val_id; + struct btf *btf; + + btf = btf__new_empty(); + if (!ASSERT_OK_PTR(btf, "btf__new_empty")) + return; + + val_id = btf__add_int(btf, "int", 4, BTF_INT_SIGNED); + if (!ASSERT_GT(val_id, 0, "btf__add_int")) + goto out; + + if (!ASSERT_OK(btf__load_into_kernel(btf), "btf__load_into_kernel")) + goto out; + btf_fd = btf__fd(btf); + + if (test__start_subtest("hash")) + check_keyless(BPF_MAP_TYPE_HASH, 0, btf_fd, val_id); + if (test__start_subtest("rhash")) + check_keyless(BPF_MAP_TYPE_RHASH, BPF_F_NO_PREALLOC, btf_fd, val_id); +out: + btf__free(btf); +} -- 2.43.0