From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pg1-f182.google.com (mail-pg1-f182.google.com [209.85.215.182]) (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 C7B974AEE2 for ; Tue, 7 Apr 2026 14:54:38 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.215.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775573680; cv=none; b=IRuEPxZIPlsPAyStdGOALFZcGKOEje4twyvdCTBZWutVYcfgBZGNpdh+17PIm2l2tHnxcCarrfKCqqpk0kXy3fxNXm6BkBnrdAGFV9t32pI5dPV6np592V3I93J785YuAQRxsDEVi24OZr/NlnJVCWUzKvwLVMBCP0AhUQoFQjc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775573680; c=relaxed/simple; bh=AwxLupIt2BmepkAUp2LdB4nomF+wbPjJ8xcKlQf9WD0=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=O5w/t7PaXWGo4Fq76FhUzk/4piXeeggYcqU0V68MmIGgxXrnAApJyDbMo3XB99i0EUpvchmpNbpONA5XrGYNapFWFwfJhPOfGDWaGw/H4Df1PeKg1mUwxGuotJ1X75j8ElWoK+V7D1567UykOIUmFigRREthy4rt5WuT6BjtH2g= 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=MFK0x8EK; arc=none smtp.client-ip=209.85.215.182 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="MFK0x8EK" Received: by mail-pg1-f182.google.com with SMTP id 41be03b00d2f7-c76cce85bd9so1885521a12.1 for ; Tue, 07 Apr 2026 07:54:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1775573678; x=1776178478; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=UXzZHHfnZlsWhHKejBKYXg/anr1Lvjvzk+lC/QUfMJU=; b=MFK0x8EKQ+ypy7QVYKP2tKyJagzo/BoHmzXqw7GyGuU8EEg8BffSdYQcAJ8HloGrqz 0JapUZeD3q5/vCN8Cq57ck6Ju9JedrDU617ZzW3XH43Zi5vFoEaqH5TjqkBspX0NAkxp K/9XndzogymTFi/YluPuHdnG/aKVs4nZCqojzA1noxoAlZ6Owk7w84Pd3YOMRkoWginy wf0vPOD7W+2sAHSlv6nPW46JNiZ9yqHVYmJcsILfP4K6t/M35cYuCkF01+VWG1cyiYaG Bvd8Xlgc2HC9iiNfvQxFayP6KWVFtd9nTT1IcDu9iAmmFN1hSus43FG5KMYcCkA+DUNW taQA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1775573678; x=1776178478; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to; bh=UXzZHHfnZlsWhHKejBKYXg/anr1Lvjvzk+lC/QUfMJU=; b=bbt9ab/+FZBw6sTZPliW8MR7sdPOESmP9yAiuA+NMHKeTtP9vXd0zInFg36ZP5nByv AM9faIYbssv1zOwlbioTUbq3/vbqgKend19fkc2Yl53BPc29fdhjeSEgi9yyQj/s/xZv hGqHQBa4BkJzlJh2Z3wxIjFPzWC0h1FPJ9ZOggZa/OYHQWb9d+4quJGhb0COw9/sDnCH GuMqzAB3eUUgx5buhnrMdp7uKG6ZUD5fSsZfsLUCR6ba3T3rsxgPWEemngjvtXl7ZPiD jB3jdye+pkyu2fmCssmuUruow37bRoP5xGxHYHA4wpJTMjFTF1SseUNj6PAW3m968FJJ Qtpw== X-Forwarded-Encrypted: i=1; AJvYcCVDIrksSSEDcRjZ69w2nygOhbRoDvo76A9RbFsCCy3Ue+mAOj068M96KIU1xoMLFewt/sQ=@vger.kernel.org X-Gm-Message-State: AOJu0YxKZH9gJ3iX9V+fecWwOrL/s8KMKDFXVCY95cdu2pIHzmff/f2G 7SVvnIxTubbwE5e8RTlFFAT7kOBsEX7Q6m1VV7BOf15/VIZQ1Pr7nJ0x X-Gm-Gg: AeBDievn/lSEX6NutXPHDYDsP5XoLCzMpTjSVsi3DwZilQTKWLUPLOcBrxZtVBRT/Sh qadvj09JGAFk+hIDciXMrlahGafDHd1DP3bVpcDfhrYfkNziB0Z0OSuxDzJMq2oO8YIJTMosaHk xolLHS/HB6LjEDT9QBrm+7ZxG/Y/U84oOGC+qHMH2CylfYQpRa/iPnQr/HeyqKPJKks8x7t6tqa A2VpG2htOEoNIpHXFAq7lgpYpE5ijr0rnPL1puv5PvE0xHJg7wh3NFn5VPFkMiX1RpRbMyU/O2S pX5KeDTzu16euSBQ1+FTaLDquAMa8Of6yQaqXt7O8OiY7jTDFl7W73VTIKUS4zyCpLUJxCiL3ep fAVieOsWwNawnhWk+5Bxe77G+S64lPSO6eQKY06LigA59RcN9thlqVNeSI2RhzL/K/utya8ggFh /kjuXz3ujD6n3Kkb+E94zQfhXfuv1MjobUo5E= X-Received: by 2002:a05:6a21:3387:b0:39f:2b9e:e486 with SMTP id adf61e73a8af0-39f2f172c0dmr16465423637.58.1775573678023; Tue, 07 Apr 2026 07:54:38 -0700 (PDT) Received: from localhost.localdomain ([47.236.127.140]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-c76c6476a81sm15755650a12.7.2026.04.07.07.54.33 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 07 Apr 2026 07:54:37 -0700 (PDT) From: Qi Tang To: Alexei Starovoitov , Daniel Borkmann Cc: Kumar Kartikeya Dwivedi , Amery Hung , Eduard Zingerman , Andrii Nakryiko , Martin KaFai Lau , Song Liu , bpf@vger.kernel.org, Qi Tang Subject: [PATCH bpf-next] selftests/bpf: add test for nullable PTR_TO_BUF access Date: Tue, 7 Apr 2026 22:54:21 +0800 Message-ID: <20260407145421.4315-1-tpluszz77@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Add iter_buf_null_fail with two tests and a test runner: - iter_buf_null_deref: verifier must reject direct dereference of ctx->key (PTR_TO_BUF | PTR_MAYBE_NULL) without a null check - iter_buf_null_check_ok: verifier must accept dereference after an explicit null check Acked-by: Kumar Kartikeya Dwivedi Reviewed-by: Amery Hung Signed-off-by: Qi Tang --- .../bpf/prog_tests/iter_buf_null_fail.c | 9 +++++ .../selftests/bpf/progs/iter_buf_null_fail.c | 39 +++++++++++++++++++ 2 files changed, 48 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/iter_buf_null_fail.c create mode 100644 tools/testing/selftests/bpf/progs/iter_buf_null_fail.c diff --git a/tools/testing/selftests/bpf/prog_tests/iter_buf_null_fail.c b/tools/testing/selftests/bpf/prog_tests/iter_buf_null_fail.c new file mode 100644 index 000000000000..ea97787b870d --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/iter_buf_null_fail.c @@ -0,0 +1,9 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include "iter_buf_null_fail.skel.h" + +void test_iter_buf_null_fail(void) +{ + RUN_TESTS(iter_buf_null_fail); +} diff --git a/tools/testing/selftests/bpf/progs/iter_buf_null_fail.c b/tools/testing/selftests/bpf/progs/iter_buf_null_fail.c new file mode 100644 index 000000000000..3daad40515e6 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/iter_buf_null_fail.c @@ -0,0 +1,39 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (c) 2026 Qi Tang */ + +#include +#include +#include "bpf_misc.h" + +char _license[] SEC("license") = "GPL"; + +/* Verify that the verifier rejects direct access to nullable PTR_TO_BUF. */ +SEC("iter/bpf_map_elem") +__failure __msg("invalid mem access") +int iter_buf_null_deref(struct bpf_iter__bpf_map_elem *ctx) +{ + /* + * ctx->key is PTR_TO_BUF | PTR_MAYBE_NULL | MEM_RDONLY. + * Direct access without null check must be rejected. + */ + volatile __u32 v = *(__u32 *)ctx->key; + + (void)v; + return 0; +} + +/* Verify that access after a null check is still accepted. */ +SEC("iter/bpf_map_elem") +__success +int iter_buf_null_check_ok(struct bpf_iter__bpf_map_elem *ctx) +{ + __u32 *key = ctx->key; + + if (!key) + return 0; + + volatile __u32 v = *key; + + (void)v; + return 0; +} -- 2.43.0