From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f67.google.com (mail-pj1-f67.google.com [209.85.216.67]) (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 A98D4385D8C for ; Wed, 10 Jun 2026 07:13:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.67 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781075632; cv=none; b=AanN1FhFQW3N2MQ80AmvItB2gL8nYTtdVVmzu4VAe5004XBvvgIrYdnFLwDJ66KEdKHlX2ae7OLGVYHtWUIZSPYLG0ueiOPC5UK5twK9+Qrn3TdAo7QlBAmKlt3dzGcc/qVNY7BsYHHsW7fjrDkCOt7eesrHMh8RzDQ1QowFlJk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781075632; c=relaxed/simple; bh=53JyhO7i5frR2tFIJKi76YP5Onuf89dbn1JJ8Mp4sJ0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:To:Cc; b=pfn/3k0duH8ilHHcV5TavSynU7/o+iCc7sVCmH6lo0IY06oXsOGEtqqZhfUs6AL2TbOrbG5vCVmDRmGQkzSMIn4xNkQE7mOxZEeDLyWJMXGehgvv2sazc9wav/AhIEsxXmdUTQLVqKaiPIE5w0hiir4OGdclnHYp9ZruGLwlUys= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=V6UFO26m; arc=none smtp.client-ip=209.85.216.67 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="V6UFO26m" Received: by mail-pj1-f67.google.com with SMTP id 98e67ed59e1d1-36b9b15af73so5970954a91.0 for ; Wed, 10 Jun 2026 00:13:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1781075630; x=1781680430; darn=vger.kernel.org; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:from:to:cc:subject:date:message-id:reply-to; bh=yzdEMh5lHMBwcaHbKYzieVMCGt4oUIEY8iF46MdpcK0=; b=V6UFO26mrR8jlINLiVfxjBhxh+OvmhJPe3xZLarevWETHG6JgRGzcKr9DiLPstL0GE TypiCqLbJVS7PDUjBMI2wSsvM9EzPJtCidVz2TvGfiVkykckj6EwgPZgYh1AbysxIqOD YQjywpFFzmxK4h2eZJeq/ts5cawwXu6XAxL0Du9kP6kVwSE0cvEeC/rXrx7vFUBJbHlP sZkTcB++MXC5HdQ05zC3sWbftURxrxacgufM/WgSQyKgArnVHumn6BN4rsbF6piSqLsk UclhWVQwH4QLWUpYlSwdRY43X5Bwsrf0OtOuXj0GiOgvnPCSOrLdYANjtTvnlD6j0YvH X7iA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1781075630; x=1781680430; h=cc:to:message-id:content-transfer-encoding:mime-version:subject :date:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=yzdEMh5lHMBwcaHbKYzieVMCGt4oUIEY8iF46MdpcK0=; b=Lguq32mubQ58S94CF3e/umNheJYQtGIhQjweWeADrKwMFNYRzYr09b3xHE4NYgBhpq ludDsp4rCpNC+QH/XHrnW4zlVH7FiWRr7sp846yG6Mezto1tqva8VooeCiUHk3iCU/J+ SHjbXg+YlEzQb0v9zHQToIk2khdth6oTIpM4XBAzasXIkhFk74A3bhUGd7Ki0lPaNtJm 7LXhNCSBBL+9lZIdYDPdGeGHdbqyB03rU70sqh060OK7ff1Kg72hYmoPHrEIImjkYayG wfELynZu3M1HbmIuu/FyvRX0h8tCDezp1gB3cvEGNMFNG7A9AG/HadXwZbdVRLToKjHW GWTw== X-Gm-Message-State: AOJu0Yzjj5tk+UqrUmcBbhlCOMO6AZJFK1DWiXzbHZzHoEPks76XpEn8 fV7WtMy1YkM60mIEsDIDxyLmkIJLbZxXytVQvLzETvucoAxWzeC8zOyO X-Gm-Gg: Acq92OH3JdeI6Wq6l3EclP45W8fdeGFxk3CquMp+eDlOfooql0Kh9XueuitIMd9p1l0 z3dYU+uRguoMkgAGlPxt9z5wRMOu2kSHff/59P1cyQr8/6ucgOPas6f5TPOsSXAQYZAE/vGYuAI 6xkI4NAEJj1WEF8GnHHZ3K68hEgeqedC1U4a4Z21tvIoCegDdLNeFr6wx6GGpYMnuoiv/E9G/bm JuZdKyNkWmj+qW/Znm3utHhPbLOamqYWZdCsbNLLEwHWdbfDcM9Dp3+XibRgZom5KzXLFsQtRfZ jyuOIx0OsDnF5W9SsOQSdmDEYnHWKibtGw0rGRNy3fNSDghMZnGGWk7ImFf3J5OMdf8dTEl/xT4 vDdvnFiidosLYwH+2sCtsKl64LH/4SHwaPfYU9Eln3Cw7K+mVAIK4L2axKT+ue7/y51tyhaauHr JBHBF26zBILAqaaOEZqNfbiz4t/PL1wT2+ X-Received: by 2002:a17:902:ef08:b0:2b9:6458:1a2c with SMTP id d9443c01a7336-2c1e820e30bmr298583035ad.13.1781075629930; Wed, 10 Jun 2026 00:13:49 -0700 (PDT) Received: from [172.30.1.91] ([59.6.68.4]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2c164f875casm237059765ad.22.2026.06.10.00.13.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 10 Jun 2026 00:13:49 -0700 (PDT) From: Woojin Ji Date: Wed, 10 Jun 2026 16:13:45 +0900 Subject: [PATCH bpf-next v3] selftests/bpf: Add arena direct-value one-past-end reject test Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260610-arena-direct-value-v1-v3-1-d5f0d935ee45@gmail.com> X-B4-Tracking: v=1; b=H4sIAAAAAAAC/4WOyw6DIBBFf6VhXRoe9dVV/6PpAnBQGkUDSmyM/ 16kGzdNk9nczJxzZ0UenAGPbqcVOQjGm8HGwM8npFphG8CmjhkxwnKSE46FAytwbRyoCQfRzYA DxaCvtS6zQlalRJEdHWizJO8DyVFjC8uEnt+Nn+Ur0rt2v22Nnwb3Ti8Emog/bXEoLiSnShFRK qHuTS9Md1FDnzoCO1qyXxYWLaJiSrKSAi/yo2Xbtg/ppg5jHAEAAA== X-Change-ID: 20260603-arena-direct-value-v1-ef4df857b98b To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa , Shuah Khan Cc: linux-kernel@vger.kernel.org, bpf@vger.kernel.org, linux-kselftest@vger.kernel.org, Emil Tsalapatis , Junyoung Jang , Woojin Ji X-Mailer: b4 0.15.2 X-Developer-Signature: v=1; a=openpgp-sha256; l=5647; i=random6.xyz@gmail.com; h=from:subject:message-id; bh=53JyhO7i5frR2tFIJKi76YP5Onuf89dbn1JJ8Mp4sJ0=; b=owEBbQKS/ZANAwAKAUOXRMMVrfhrAcsmYgBqKQ6q/0Mnw8OjeZLWplgHEnkOYShXxKmetW4OQ f6Q92Vn4+mJAjMEAAEKAB0WIQSrknTJbxUcAdPNt5BDl0TDFa34awUCaikOqgAKCRBDl0TDFa34 axveEACfexJ/1G1cZljjcqjlGuRWEziCRKgYU15g/chjQTl7g7ce7+MNBPJURxttv7VmgW8uZyM secmTrgsg4TwTKq6Wfskg2RjJe3P4PRdILTfmNrUtP16bH3UqHC9Btq0vJsgv7jTOz29wlt2I4a MVjM3D9QsjZCG5Di0aMYscwcDJXJ4qhfHDeS53PoIeEekdyeB77nH08zgqScL/x0rT3WpCmniwt SxIJe/bsgZeDHafcB8uj69SD06r+wp7TcbRZ0h5VyOJmDmer/AUAxa+6t2A41t5akW4DRoI4eE1 AmygEVyo3tIp7mVxCaTnlhlzw2aIIu77F6iqFaCyPQaBDCKVzksuW0ntC705i6r0NzgQaecTCfE BvxShBIn1RXvR79xlWWVICvn+mpQ6YI/lod57n6L5EaTVPI6k2ugHAfl5wbolZhlvUJNEE3i7Qd syNJdaATVgpv1EJE0dd6cUx/66H5EFzraxcUhnoDDqk0VLGQ+RHhyErtRYgO07OGYPsouZe41j3 sB0nMJlUuqn6jijDuLbwpiXwz6+hnjx4b3O3qCYqKEZ/AbtZJK0PP5H2JI7RjcVJS34iLOhbSTM jsFBgEn98SICUzKnrdTRITXJ2oWZmSzPm+mMs/Vx6Mwu4HM4JfvBFXhJvuBCe1T8X0cTgLLF0qQ WFf8czg0/HWX1Cg== X-Developer-Key: i=random6.xyz@gmail.com; a=openpgp; fpr=AB9274C96F151C01D3CDB790439744C315ADF86B BPF_MAP_TYPE_ARENA supports direct-value pseudo loads, but unlike array maps its map value_size is zero and the valid direct-value range is the arena mmap size, max_entries * PAGE_SIZE. Commit 3ac1a467e376 ("bpf: Fix off-by-one boundary validation in arena direct-value access") fixed arena_map_direct_value_addr() to reject an offset exactly at the end of the arena mapping. Add a regression test that loads a BPF_PSEUDO_MAP_VALUE with off == arena_size and verifies that the verifier rejects it with the expected offset in the log. This is intentionally kept as a userspace raw-instruction test. I tried expressing the same BPF_PSEUDO_MAP_VALUE + off == arena_size case in verifier_arena.c with inline assembly. The only form that produces the desired instruction bytes uses __imm_addr(arena), but that emits R_BPF_64_NODYLD32, which the libbpf/bpftool link step rejects. Other register, immediate, and memory constraints either fail in the BPF backend or lower to a normal R_BPF_64_64 load followed by an ALU add, which does not exercise arena_map_direct_value_addr() with the boundary offset in the second ldimm64 slot. A legacy test_verifier fixture can express the raw instruction directly, but it needs arena map creation, mmap, and fixup plumbing in the legacy runner. That is more intrusive than the small prog_tests raw-instruction test. Use the userspace raw-instruction test, following the existing selftests pattern used for direct map-value pseudo loads, so insns[1].imm can be set to arena_size precisely. Assisted-by: ChatGPT:gpt-5.5 Signed-off-by: Woojin Ji Cc: Emil Tsalapatis Cc: Junyoung Jang --- Changes in v3: - Document why verifier_arena.c inline assembly cannot express this case: __imm_addr emits R_BPF_64_NODYLD32, while other constraints either fail in the BPF backend or miss the pseudo-load boundary path. - Mention that natural C forms lower to a normal load plus ALU add, so they do not exercise arena_map_direct_value_addr() with off == arena_size. - Keep the userspace raw-instruction test as the least intrusive option; test_verifier was checked but would require legacy runner arena plumbing. - Link to v2: https://patch.msgid.link/20260605-arena-direct-value-v1-v2-1-a92cb281e376@gmail.com Changes in v2: - Explain why this uses a userspace raw-instruction test rather than a verifier_arena.c failure program: the test must set the second BPF_PSEUDO_MAP_VALUE ldimm64 immediate to arena_size exactly. For arena globals, libbpf derives that immediate from the arena-relative symbol offset, so the boundary value cannot be represented directly as a verifier_arena.c C-level failure program. - Link to v1: https://patch.msgid.link/20260603-arena-direct-value-v1-v1-1-7b31cc0a8cac@gmail.com Tested on x86_64 with tools/testing/selftests/bpf/vmtest.sh: $ ./test_progs -t arena_direct_value #2/1 arena_direct_value/one_past_end:OK #2 arena_direct_value:OK Summary: 1/1 PASSED, 0 SKIPPED, 0 FAILED --- .../selftests/bpf/prog_tests/arena_direct_value.c | 73 ++++++++++++++++++++++ 1 file changed, 73 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/arena_direct_value.c b/tools/testing/selftests/bpf/prog_tests/arena_direct_value.c new file mode 100644 index 000000000000..b7760b021670 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/arena_direct_value.c @@ -0,0 +1,73 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include +#include +#include + +#define ARENA_PAGES 32 + +static void test_arena_direct_value_one_past_end(void) +{ + char log_buf[16384] = {}, expected[128]; + __u32 arena_sz = ARENA_PAGES * getpagesize(); + struct bpf_insn insns[] = { + BPF_LD_IMM64_RAW(BPF_REG_1, BPF_PSEUDO_MAP_VALUE, 0), + BPF_MOV64_IMM(BPF_REG_0, 0), + BPF_EXIT_INSN(), + }; + LIBBPF_OPTS(bpf_map_create_opts, map_opts); + LIBBPF_OPTS(bpf_prog_load_opts, prog_opts); + void *arena = MAP_FAILED; + int map_fd, prog_fd; + + map_opts.map_flags = BPF_F_MMAPABLE; + prog_opts.log_buf = log_buf; + prog_opts.log_size = sizeof(log_buf); + prog_opts.log_level = 1; + + map_fd = bpf_map_create(BPF_MAP_TYPE_ARENA, "arena_direct_value", + 0, 0, ARENA_PAGES, &map_opts); + if (map_fd < 0) { + if (errno == EOPNOTSUPP || errno == EINVAL) { + test__skip(); + return; + } + ASSERT_GE(map_fd, 0, "bpf_map_create"); + return; + } + + arena = mmap(NULL, arena_sz, PROT_READ | PROT_WRITE, MAP_SHARED, map_fd, 0); + if (!ASSERT_NEQ(arena, MAP_FAILED, "arena_mmap")) + goto cleanup; + + insns[0].imm = map_fd; + insns[1].imm = arena_sz; + + prog_fd = bpf_prog_load(BPF_PROG_TYPE_RAW_TRACEPOINT, + "arena_direct_value", "GPL", insns, + ARRAY_SIZE(insns), &prog_opts); + if (!ASSERT_LT(prog_fd, 0, "prog_load")) { + if (prog_fd >= 0) + close(prog_fd); + prog_fd = -1; + goto cleanup; + } + + snprintf(expected, sizeof(expected), + "invalid access to map value pointer, value_size=0 off=%u", + arena_sz); + ASSERT_HAS_SUBSTR(log_buf, expected, "verifier_log"); + +cleanup: + if (arena != MAP_FAILED) + munmap(arena, arena_sz); + close(map_fd); +} + +void test_arena_direct_value(void) +{ + if (test__start_subtest("one_past_end")) + test_arena_direct_value_one_past_end(); +} --- base-commit: ba3e43a9e601636f5edb54e259a74f96ca3b8fd8 change-id: 20260603-arena-direct-value-v1-ef4df857b98b Best regards, -- Woojin Ji