From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm1-f47.google.com (mail-wm1-f47.google.com [209.85.128.47]) (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 A9E9B225788 for ; Fri, 22 May 2026 21:15:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.47 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779484521; cv=none; b=AO4qEBBUpYIt92HMez9LT4JzXETmPGuP6eX5fve0oeuqu9ZpgzveYpjx4BaQwnok0Xqwu5HZWbRBZAEnvoaY2TH3dujrC+jo2SC2dUhhZSSwOX/e3WlMSSYX1ez8/hq6Zst9Mx4brED6jiFMe9J6+mlHZ00ymlXrDDmQYVpzjUs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779484521; c=relaxed/simple; bh=0bQw2teXIDcwN3yYNKQ7goKkNy4catNzdl4bx9r8JhY=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=Vubxd9VduzK21CT6ZmTnOK6w13SkoCo+MzexRUiaIq5Tj2Aqth7/HnOWpj65HpSCa+Gl7ocJNfBSus30qFZHVq5DrAAr0o+YoVaOUg37Yy6FSIPGmcHvujY5dSvuTZkmgJ7cpGulcgk26fYLFtMrUeunEXPhUEvFNxswtPUD7NE= 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=BjWIVnS+; arc=none smtp.client-ip=209.85.128.47 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="BjWIVnS+" Received: by mail-wm1-f47.google.com with SMTP id 5b1f17b1804b1-4903d730b1fso18585455e9.2 for ; Fri, 22 May 2026 14:15:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1779484518; x=1780089318; 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=q4E9RiNY5xxeH8v0CHIC9N3hVDQi7OzQEt/odZrgvSk=; b=BjWIVnS+4iDsOZHuOvx7rVAX1oR9dESF23xWClOqOt+gwrrUwH9vYVIdYHpTT1fQuZ NkD91LEAILe7823YFbStEOdMOxrtK91OH5KuUML9pfeYjr46inRAbUf+Yhr8I6exRgnG B3KGpHBbX8uk4XrU5ueDs2UFSYJbhStOoLcANX4Zt0ZivWIBXNFQu1KMjgW9XLgiDW4T sSd9D6QgB/hy1Ev3a5SUvhKM/KlXK+dtq9ufBLFVN72AxM09xp1zGcdkD08he6PacF9N nT/o62lIpIJJCZzhYtwOEBXe4gGOSmiCeUfSoZ9ZyJ1P++DXxt9xL+eXNr4l/cJmHKFD ehzg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779484518; x=1780089318; 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=q4E9RiNY5xxeH8v0CHIC9N3hVDQi7OzQEt/odZrgvSk=; b=hXCme2mlirlpjt8iMt1nLYqoI7TY/ZvHqGNjs6XM1KFutonUXSh4qq7g3KvVVYn4M2 u1Nt5kr8FUZPj6jfn0o6XxaEci/nMg7JxcHuE9NvkE7CxoXcydEhYTNv0SCItqZP2xUE cKgdFLRw3XPXoUI6fDdAZhmCreAHHQuf8TKrgQG3x6KxTG1Jx4tMXT4p7PMtV7d4LVPo wkyZIGcYcg+90cgSqT1kQ5Fa+lZ1X8Py9vMQOcevVJVdWU49sy0S7oTI+uXl2ne1tfbF K/jvD+u+qdXzCIW7wyaQDghnylrTDxk9v+KlbFx9sZRMj9v2ezaFORgPCXc2eF701s+T VQiQ== X-Forwarded-Encrypted: i=1; AFNElJ8qUculC+F0pcWu5oRBUx9GAe0KQ5xrDrsUjQ/lTWBzaWNqZvb1vwSc/eZg7zgla7BBCBRhS9k=@vger.kernel.org X-Gm-Message-State: AOJu0YzFvAaLNZ3UTxmd0YJOmyRk6xBSX9W6hR6YQ3qE58ocjigxmlV/ HC+duJT8aLN8BlOz3icxh6s8xb85yJBsurL7BAzguigAASGyRx9DaUOp X-Gm-Gg: Acq92OFPDvWcuKVmc7DAhhNNy1HlxLloecH0Vb4E5smN2UMv9jubo7K14RSOLGbC3da l1prUHYOl0J6FN3FxVbaMs2wwJ8YBvQsbYjZ6XYBFuvMEC+yPtHjkrcXXoF9JjJfVliZwMmu7qn hLk91pXswfUNZ5cRsFM/RRkacudgCjIEQ3lWgSwWpcmlFYmsiEURvgGjJQleHRVGN5LdAM+Mbr0 aiD2Y19Pl0a5TQBgxap/oksO0VPWyRATDWEWb1zmiSwm1tKR/TFN9TxZiwMUtIogNHg1xUGj6Z/ Gej1jvU3CiB9N8Vpnu/Ij/dJ1vLIjsnBtdaGH//8ftkBzsWF/17TR/rZLpucz97LeeDevyK1eya bdfGv1GsouBW9QJBLNLuatc08eZxXXNCSQ/tQHwMpiJauBxtLRy5nL5JcrwU7pwsgUCxnII4eCA 5wB2pfZ3H+orEvB9xBVBt9CtUlwAhJjgZN9QSq1qGQA+snljecvsihkCBdtvc1cFTSkSR9v88hZ 7dSgE34NrT1o6N5WDASkGTB+KdbEznTNfcTP2v1ujs/OffQL0a07KNdnRFZnrKlfTnmga2qRPg3 h7vqTYaQPLriGEOBafKz843oSwBMeoTfbkP3LTX+pw== X-Received: by 2002:a05:600c:4ecc:b0:485:30d4:6b9e with SMTP id 5b1f17b1804b1-490426cd8a4mr74193815e9.21.1779484517821; Fri, 22 May 2026 14:15:17 -0700 (PDT) Received: from localhost.localdomain (dynamic-2a02-3100-ada3-3901-ad33-2cf3-cf37-617f.310.pool.telefonica.de. [2a02:3100:ada3:3901:ad33:2cf3:cf37:617f]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49044775266sm22135525e9.33.2026.05.22.14.15.15 (version=TLS1_3 cipher=TLS_CHACHA20_POLY1305_SHA256 bits=256/256); Fri, 22 May 2026 14:15:16 -0700 (PDT) From: Karl Mehltretter To: Russell King Cc: Linus Walleij , "Russell King (Oracle)" , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org, Karl Mehltretter Subject: [PATCH] ARM: entry: use byte load for KASAN VMAP stack shadow Date: Fri, 22 May 2026 23:15:03 +0200 Message-Id: <20260522211503.25219-1-kmehltretter@gmail.com> X-Mailer: git-send-email 2.39.5 (Apple Git-154) Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Commit 44e9a3bb76e5 ("ARM: 9430/1: entry: Do a dummy read from VMAP shadow") added a dummy read from the KASAN VMAP stack shadow in __switch_to(). The read uses ldr, but KASAN shadow memory is byte-granular and the computed shadow address is not guaranteed to be word aligned. Booting the QEMU versatilepb machine with an ARM926EJ-S CPU and CONFIG_KASAN=y, CONFIG_KASAN_VMALLOC=y and CONFIG_VMAP_STACK=y faults before init: Unhandled fault: alignment exception (0x001) at 0xb91037f6 PC is at __switch_to+0x64/0x88 Use ldrb for the dummy shadow access. The code only needs to fault if the shadow mapping is missing, so a byte load is sufficient and matches the granularity of KASAN shadow memory. Fixes: 44e9a3bb76e5 ("ARM: 9430/1: entry: Do a dummy read from VMAP shadow") Cc: stable@vger.kernel.org # v6.13+ Assisted-by: Codex:gpt-5 Signed-off-by: Karl Mehltretter --- arch/arm/kernel/entry-armv.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm/kernel/entry-armv.S b/arch/arm/kernel/entry-armv.S index ef6a657c8d13..a3d050ce9b79 100644 --- a/arch/arm/kernel/entry-armv.S +++ b/arch/arm/kernel/entry-armv.S @@ -567,7 +567,7 @@ ENTRY(__switch_to) @ are using KASAN mov_l r2, KASAN_SHADOW_OFFSET add r2, r2, ip, lsr #KASAN_SHADOW_SCALE_SHIFT - ldr r2, [r2] + ldrb r2, [r2] #endif #endif -- 2.39.5 (Apple Git-154)