From nobody Sun Nov 10 20:44:10 2024 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id DBA7BC6FA99 for ; Wed, 8 Mar 2023 02:21:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229730AbjCHCVV (ORCPT ); Tue, 7 Mar 2023 21:21:21 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229483AbjCHCVS (ORCPT ); Tue, 7 Mar 2023 21:21:18 -0500 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7A5C4A6499 for ; Tue, 7 Mar 2023 18:21:06 -0800 (PST) X-UUID: ddc234eabd5711eda06fc9ecc4dadd91-20230308 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Type:Content-Transfer-Encoding:MIME-Version:Message-ID:Date:Subject:CC:To:From; bh=13Wy0Ed++1zXh0KzmnLa4BZ0fSU9hMpfdWuFisECxUA=; b=p9xVSjlu85X97VqmsUP1EoW0h7c+G3qBfxHAdOFe7FoOdXDWNvMtir6WIiFA4FeWwqVhTDZInK7b4JglgZ2KQS7y55qmgjH9csmxPv6Lr6skGBBAzAKXdxGs/no91MmloS0gswgAerheuZ5/vspbbNKSEgeCM94nELVWv8V6bu4=; X-CID-CACHE: Type:Local,Time:202303081011+08,HitQuantity:1 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.20,REQID:52d32188-1362-4898-a3a5-ebd9b2f65e21,IP:0,U RL:0,TC:0,Content:0,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_Ham,ACTION: release,TS:0 X-CID-META: VersionHash:25b5999,CLOUDID:57e616f5-ddba-41c3-91d9-10eeade8eac7,B ulkID:nil,BulkQuantity:0,Recheck:0,SF:102,TC:nil,Content:0,EDM:-3,IP:nil,U RL:11|1,File:nil,Bulk:nil,QS:nil,BEC:nil,COL:0,OSI:0,OSA:0,AV:0 X-CID-BVR: 0,NGT X-UUID: ddc234eabd5711eda06fc9ecc4dadd91-20230308 Received: from mtkmbs11n1.mediatek.inc [(172.21.101.185)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1123491311; Wed, 08 Mar 2023 10:20:59 +0800 Received: from mtkmbs11n2.mediatek.inc (172.21.101.187) by mtkmbs13n2.mediatek.inc (172.21.101.108) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.1118.25; Wed, 8 Mar 2023 10:20:59 +0800 Received: from mszsdtlt102.gcn.mediatek.inc (10.16.4.142) by mtkmbs11n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.1118.25 via Frontend Transport; Wed, 8 Mar 2023 10:20:58 +0800 From: Haibo Li To: Marco Elver CC: Dmitry Vyukov , Matthias Brugger , AngeloGioacchino Del Regno , , , , , , Subject: [PATCH] kcsan:fix alignment_fault when read unaligned instrumented memory Date: Wed, 8 Mar 2023 10:20:57 +0800 Message-ID: <20230308022057.151078-1-haibo.li@mediatek.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-MTK: N Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" After enable kcsan on arm64+linux-5.15,it reports alignment_fault when access unaligned address. Here is the oops log: " Trying to unpack rootfs image as initramfs..... Unable to handle kernel paging request at virtual address ffffff802a0d8d7171 Mem abort info:o: ESR =3D 0x9600002121 EC =3D 0x25: DABT (current EL), IL =3D 32 bitsts SET =3D 0, FnV =3D 0 0 EA =3D 0, S1PTW =3D 0 0 FSC =3D 0x21: alignment fault Data abort info:o: ISV =3D 0, ISS =3D 0x0000002121 CM =3D 0, WnR =3D 0 0 swapper pgtable: 4k pages, 39-bit VAs, pgdp=3D000000002835200000 [ffffff802a0d8d71] pgd=3D180000005fbf9003, p4d=3D180000005fbf9003, pud=3D180000005fbf9003, pmd=3D180000005fbe8003, pte=3D006800002a0d8707 Internal error: Oops: 96000021 [#1] PREEMPT SMP Modules linked in: CPU: 2 PID: 45 Comm: kworker/u8:2 Not tainted 5.15.78-android13-8-g63561175bbda-dirty #1 ... pc : kcsan_setup_watchpoint+0x26c/0x6bc lr : kcsan_setup_watchpoint+0x88/0x6bc sp : ffffffc00ab4b7f0 x29: ffffffc00ab4b800 x28: ffffff80294fe588 x27: 0000000000000001 x26: 0000000000000019 x25: 0000000000000001 x24: ffffff80294fdb80 x23: 0000000000000000 x22: ffffffc00a70fb68 x21: ffffff802a0d8d71 x20: 0000000000000002 x19: 0000000000000000 x18: ffffffc00a9bd060 x17: 0000000000000001 x16: 0000000000000000 x15: ffffffc00a59f000 x14: 0000000000000001 x13: 0000000000000000 x12: ffffffc00a70faa0 x11: 00000000aaaaaaab x10: 0000000000000054 x9 : ffffffc00839adf8 x8 : ffffffc009b4cf00 x7 : 0000000000000000 x6 : 0000000000000007 x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffffffc00a70fb70 x2 : 0005ff802a0d8d71 x1 : 0000000000000000 x0 : 0000000000000000 Call trace: kcsan_setup_watchpoint+0x26c/0x6bc __tsan_read2+0x1f0/0x234 inflate_fast+0x498/0x750 zlib_inflate+0x1304/0x2384 __gunzip+0x3a0/0x45c gunzip+0x20/0x30 unpack_to_rootfs+0x2a8/0x3fc do_populate_rootfs+0xe8/0x11c async_run_entry_fn+0x58/0x1bc process_one_work+0x3ec/0x738 worker_thread+0x4c4/0x838 kthread+0x20c/0x258 ret_from_fork+0x10/0x20 Code: b8bfc2a8 2a0803f7 14000007 d503249f (78bfc2a8) ) Reported-by: Haibo Li ---[ end trace 613a943cb0a572b6 ]----- " After checking linux 6.3-rc1 on QEMU arm64,it still has the possibility to read unaligned address in read_instrumented_memory(qemu can not emulate alignment fault) To fix alignment fault and read the value of instrumented memory more effective,bypass the unaligned access in read_instrumented_memory. Signed-off-by: Haibo Li --- kernel/kcsan/core.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/kernel/kcsan/core.c b/kernel/kcsan/core.c index 54d077e1a2dc..88e75d7d85d2 100644 --- a/kernel/kcsan/core.c +++ b/kernel/kcsan/core.c @@ -337,6 +337,11 @@ static void delay_access(int type) */ static __always_inline u64 read_instrumented_memory(const volatile void *p= tr, size_t size) { + bool aligned_read =3D (size =3D=3D 1) || IS_ALIGNED((unsigned long)ptr, s= ize); + + if (!aligned_read) + return 0; + switch (size) { case 1: return READ_ONCE(*(const u8 *)ptr); case 2: return READ_ONCE(*(const u16 *)ptr); --=20 2.25.1