From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 43E48367298 for ; Thu, 3 Sep 2026 18:42:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788460929; cv=none; b=PAB+rbiY1eBpaJzqReQ9cxcS+d/n/XkowI+Ijk9A7dlhov07FhxQvbN7Nvfm7HCW49syz7Fc+/H38eZql2hz0EmpGvZOR/WAHYuM3yI6VylS5AyXxHoq7KO8+q5Zee9NLsisXJXlPS/gCbiTwAc/d9uL7eHN6R7cPxEUhD3u6VE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788460929; c=relaxed/simple; bh=QkYe8yMaTGHhvKHkBL9jPv4MRfYFWAJwY5Y1LklcES4=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=NatCNPizm/oN/EBdY8aooChgch6b0flTtnIrUD2lTFWbywYocpzjhsa/5iOfjNm/Q+AphnzqO/kHNnhQtHP4W3nAcOQspdvZ+j90UZEV91UZUYvKgofOBy48AqtihkRlH9x3wHoI0nghTe3Hw/2s7aIzAtI3PKRBFduJsv0W8qk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=Pxd00T3h; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="Pxd00T3h" Received: by smtp.kernel.org (Postfix) with ESMTPSA id CA5AA1F000E9; Thu, 3 Sep 2026 18:41:59 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788460921; bh=sNeZgb44musgSTavs9Kw4MJhdrTxoxH08MKOF8nphzM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=Pxd00T3hA42xl/WDN/YSoNLi/GQ//DVSYaBe+7xKbPlgu8a0mrJ9lDQt6rgM53V/X VgJaDxnvBI9tkcv22GT04/IW9ZFcbjNH3qNANaYNnqGMA1GaVIbJcVDlXG1Ex5S5aR TZmHPCgxQ+6EYJQa3vN6PEFR7wu+w1x5nmLD5I5io/WWbb2yEEuyQi6rvxPdTHcsDU d6Qy+NuB46f2r93seud1Ll8t8NRMb2pTmZ3DyfXQLgUBSK7K3E81CUepZWghzDavmk PWbCXO3w1gC5JRfFK5c++zKRbC4d4q0sobBJ6fb7VCOaNcgrFcjjTDo7nS2zcWxxHh EDF1iI+ULwxfw== From: Nathan Chancellor To: gregkh@linuxfoundation.org, stable@vger.kernel.org Cc: justinstitt@google.com, kees@kernel.org, morbo@google.com, ndesaulniers@google.com, rppt@kernel.org, Nathan Chancellor , Andrew Morton Subject: [PATCH stable] arch_numa: avoid false positive fortify warning in setup_node_to_cpumask_map() Date: Thu, 3 Sep 2026 11:40:37 -0700 Message-ID: <20260903184036.3827332-2-nathan@kernel.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <2026090312-geometry-relax-b127@gregkh> References: <2026090312-geometry-relax-b127@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit commit f2b1cb39d5ccab090d8353788f186f7e7a1fffd4 upstream. When building ARCH=riscv using clang with CONFIG_FORTIFY_SOURCE and CONFIG_UBSAN_BOUNDS enabled, CONFIG_NR_CPUS > 64, and the default value of 2 for CONFIG_NODES_SHIFT, there is a compiletime warning from the fortify routines. In file included from mm/arch_numa.c:11: In file included from include/linux/acpi.h:14: In file included from include/linux/resource_ext.h:11: In file included from include/linux/slab.h:17: In file included from include/linux/gfp.h:7: In file included from include/linux/mmzone.h:8: In file included from include/linux/spinlock.h:60: In file included from include/linux/interrupt_rc.h:17: In file included from include/linux/smp.h:13: In file included from include/linux/cpumask.h:11: In file included from include/linux/bitmap.h:13: In file included from include/linux/string.h:383: include/linux/fortify-string.h:430:4: warning: call to '__write_overflow_field' declared with 'warning' attribute: detected write beyond size of field (1st parameter); maybe use struct_group()? [-Wattribue-warning] 430 | __write_overflow_field(p_size_field, size); | ^ include/linux/fortify-string.h:430:4: note: called by function 'fortify_memset_chk(unsigned long, unsigned long, unsigned long)' include/linux/bitmap.h:248:3: note: inlined by function 'setup_node_to_cpumask_map' 248 | memset(dst, 0, len); | ^ include/linux/fortify-string.h:462:25: note: expanded from macro 'memset' 462 | #define memset(p, c, s) __fortify_memset_chk(p, c, s, \ | ^ include/linux/fortify-string.h:453:2: note: expanded from macro '__fortify_memset_chk' 453 | fortify_memset_chk(__fortify_size, p_size, p_size_field), \ | ^ include/linux/fortify-string.h:430:4: note: use '-gline-directives-only' (implied by '-g1') or higher for more accurate inlining chain locations 430 | __write_overflow_field(p_size_field, size); | ^ 1 warning generated. In this configuration, MAX_NUMNODES is 4. clang unrolls the for loop in setup_node_to_cpumask_map() past this, which triggers the fortify check when accessing node_to_cpumask_map on the theoretical fifth loop iteration because it would be an out of bounds write. Make it clear to clang that nr_node_ids is bounded by MAX_NUMNODES due to the logic in setup_nr_node_ids() by early returning in setup_node_to_cpumask_map() should that condition be violated. Link: https://lore.kernel.org/20260813-arch_numa-avoid-fortify-warning-v2-1-093ad97a78df@kernel.org Signed-off-by: Nathan Chancellor Closes: https://github.com/ClangBuiltLinux/linux/issues/2174 Reviewed-by: Mike Rapoport (Microsoft) Cc: Kees Cook Cc: Bill Wendling Cc: Justin Stitt Cc: Nathan Chancellor Cc: Nick Desaulniers Cc: Signed-off-by: Andrew Morton Signed-off-by: Nathan Chancellor --- This version should apply cleanly to all supported stable branches. drivers/base/arch_numa.c | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/drivers/base/arch_numa.c b/drivers/base/arch_numa.c index c99f2ab105e5..a36c939b8e90 100644 --- a/drivers/base/arch_numa.c +++ b/drivers/base/arch_numa.c @@ -105,6 +105,18 @@ static void __init setup_node_to_cpumask_map(void) if (nr_node_ids == MAX_NUMNODES) setup_nr_node_ids(); + /* + * This check should never be true but it makes it clear to compilers + * that node_to_cpumask_map is bound by nr_node_ids, avoiding false + * positive fortify warnings when accessing node_to_cpumask_map in the + * for loop below. + */ + if (unlikely(nr_node_ids > MAX_NUMNODES)) { + pr_err("nr_node_ids (%u) is larger than MAX_NUMNODES (%u)\n", + nr_node_ids, MAX_NUMNODES); + return; + } + /* allocate and clear the mapping */ for (node = 0; node < nr_node_ids; node++) { alloc_bootmem_cpumask_var(&node_to_cpumask_map[node]); -- 2.55.0