From patchwork Wed Oct 27 02:29:07 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chen Huang X-Patchwork-Id: 12586131 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 mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 76558C433FE for ; Wed, 27 Oct 2021 02:15:06 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 229C4610A0 for ; Wed, 27 Oct 2021 02:15:06 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 229C4610A0 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id A2ECE940008; Tue, 26 Oct 2021 22:15:05 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9DE07940007; Tue, 26 Oct 2021 22:15:05 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8CC93940008; Tue, 26 Oct 2021 22:15:05 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0062.hostedemail.com [216.40.44.62]) by kanga.kvack.org (Postfix) with ESMTP id 7DDF8940007 for ; Tue, 26 Oct 2021 22:15:05 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 3DAD628486 for ; Wed, 27 Oct 2021 02:15:05 +0000 (UTC) X-FDA: 78740599770.27.CBE353B Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by imf02.hostedemail.com (Postfix) with ESMTP id 93786700170A for ; Wed, 27 Oct 2021 02:15:00 +0000 (UTC) Received: from dggemv711-chm.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4HfBws6886zbhPY; Wed, 27 Oct 2021 10:10:21 +0800 (CST) Received: from kwepemm600008.china.huawei.com (7.193.23.88) by dggemv711-chm.china.huawei.com (10.1.198.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.15; Wed, 27 Oct 2021 10:14:59 +0800 Received: from localhost.localdomain (10.175.112.125) by kwepemm600008.china.huawei.com (7.193.23.88) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.15; Wed, 27 Oct 2021 10:14:58 +0800 From: Chen Huang To: Catalin Marinas , Will Deacon , Robin Murphy , Greg Kroah-Hartman CC: , , , , Chen Huang , Al Viro Subject: [PATCH 4.19.y] arm64: Avoid premature usercopy failure Date: Wed, 27 Oct 2021 02:29:07 +0000 Message-ID: <20211027022907.2617558-1-chenhuang5@huawei.com> X-Mailer: git-send-email 2.25.1 MIME-Version: 1.0 X-Originating-IP: [10.175.112.125] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To kwepemm600008.china.huawei.com (7.193.23.88) X-CFilter-Loop: Reflected X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 93786700170A X-Stat-Signature: 8yizuam39of1p67yz75aq7ra1qxy68kz Authentication-Results: imf02.hostedemail.com; dkim=none; spf=pass (imf02.hostedemail.com: domain of chenhuang5@huawei.com designates 45.249.212.188 as permitted sender) smtp.mailfrom=chenhuang5@huawei.com; dmarc=pass (policy=none) header.from=huawei.com X-HE-Tag: 1635300900-320062 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: From: Robin Murphy commit 295cf156231ca3f9e3a66bde7fab5e09c41835e0 upstream. Al reminds us that the usercopy API must only return complete failure if absolutely nothing could be copied. Currently, if userspace does something silly like giving us an unaligned pointer to Device memory, or a size which overruns MTE tag bounds, we may fail to honour that requirement when faulting on a multi-byte access even though a smaller access could have succeeded. Add a mitigation to the fixup routines to fall back to a single-byte copy if we faulted on a larger access before anything has been written to the destination, to guarantee making *some* forward progress. We needn't be too concerned about the overall performance since this should only occur when callers are doing something a bit dodgy in the first place. Particularly broken userspace might still be able to trick generic_perform_write() into an infinite loop by targeting write() at an mmap() of some read-only device register where the fault-in load succeeds but any store synchronously aborts such that copy_to_user() is genuinely unable to make progress, but, well, don't do that... CC: stable@vger.kernel.org Reported-by: Chen Huang Suggested-by: Al Viro Reviewed-by: Catalin Marinas Signed-off-by: Robin Murphy Link: https://lore.kernel.org/r/dc03d5c675731a1f24a62417dba5429ad744234e.1626098433.git.robin.murphy@arm.com Signed-off-by: Will Deacon Signed-off-by: Chen Huang --- arch/arm64/lib/copy_from_user.S | 13 ++++++++++--- arch/arm64/lib/copy_in_user.S | 20 ++++++++++++++------ arch/arm64/lib/copy_to_user.S | 14 +++++++++++--- 3 files changed, 35 insertions(+), 12 deletions(-) diff --git a/arch/arm64/lib/copy_from_user.S b/arch/arm64/lib/copy_from_user.S index 96b22c0fa343..7cd6eeaa216c 100644 --- a/arch/arm64/lib/copy_from_user.S +++ b/arch/arm64/lib/copy_from_user.S @@ -39,7 +39,7 @@ .endm .macro ldrh1 ptr, regB, val - uao_user_alternative 9998f, ldrh, ldtrh, \ptr, \regB, \val + uao_user_alternative 9997f, ldrh, ldtrh, \ptr, \regB, \val .endm .macro strh1 ptr, regB, val @@ -47,7 +47,7 @@ .endm .macro ldr1 ptr, regB, val - uao_user_alternative 9998f, ldr, ldtr, \ptr, \regB, \val + uao_user_alternative 9997f, ldr, ldtr, \ptr, \regB, \val .endm .macro str1 ptr, regB, val @@ -55,7 +55,7 @@ .endm .macro ldp1 ptr, regB, regC, val - uao_ldp 9998f, \ptr, \regB, \regC, \val + uao_ldp 9997f, \ptr, \regB, \regC, \val .endm .macro stp1 ptr, regB, regC, val @@ -63,9 +63,11 @@ .endm end .req x5 +srcin .req x15 ENTRY(__arch_copy_from_user) uaccess_enable_not_uao x3, x4, x5 add end, x0, x2 + mov srcin, x1 #include "copy_template.S" uaccess_disable_not_uao x3, x4 mov x0, #0 // Nothing to copy @@ -74,6 +76,11 @@ ENDPROC(__arch_copy_from_user) .section .fixup,"ax" .align 2 +9997: cmp dst, dstin + b.ne 9998f + // Before being absolutely sure we couldn't copy anything, try harder +USER(9998f, ldtrb tmp1w, [srcin]) + strb tmp1w, [dst], #1 9998: sub x0, end, dst // bytes not copied uaccess_disable_not_uao x3, x4 ret diff --git a/arch/arm64/lib/copy_in_user.S b/arch/arm64/lib/copy_in_user.S index e56c705f1f23..b20d3a0b3237 100644 --- a/arch/arm64/lib/copy_in_user.S +++ b/arch/arm64/lib/copy_in_user.S @@ -40,34 +40,36 @@ .endm .macro ldrh1 ptr, regB, val - uao_user_alternative 9998f, ldrh, ldtrh, \ptr, \regB, \val + uao_user_alternative 9997f, ldrh, ldtrh, \ptr, \regB, \val .endm .macro strh1 ptr, regB, val - uao_user_alternative 9998f, strh, sttrh, \ptr, \regB, \val + uao_user_alternative 9997f, strh, sttrh, \ptr, \regB, \val .endm .macro ldr1 ptr, regB, val - uao_user_alternative 9998f, ldr, ldtr, \ptr, \regB, \val + uao_user_alternative 9997f, ldr, ldtr, \ptr, \regB, \val .endm .macro str1 ptr, regB, val - uao_user_alternative 9998f, str, sttr, \ptr, \regB, \val + uao_user_alternative 9997f, str, sttr, \ptr, \regB, \val .endm .macro ldp1 ptr, regB, regC, val - uao_ldp 9998f, \ptr, \regB, \regC, \val + uao_ldp 9997f, \ptr, \regB, \regC, \val .endm .macro stp1 ptr, regB, regC, val - uao_stp 9998f, \ptr, \regB, \regC, \val + uao_stp 9997f, \ptr, \regB, \regC, \val .endm end .req x5 +srcin .req x15 ENTRY(__arch_copy_in_user) uaccess_enable_not_uao x3, x4, x5 add end, x0, x2 + mov srcin, x1 #include "copy_template.S" uaccess_disable_not_uao x3, x4 mov x0, #0 @@ -76,6 +78,12 @@ ENDPROC(__arch_copy_in_user) .section .fixup,"ax" .align 2 +9997: cmp dst, dstin + b.ne 9998f + // Before being absolutely sure we couldn't copy anything, try harder +USER(9998f, ldtrb tmp1w, [srcin]) +USER(9998f, sttrb tmp1w, [dst]) + add dst, dst, #1 9998: sub x0, end, dst // bytes not copied uaccess_disable_not_uao x3, x4 ret diff --git a/arch/arm64/lib/copy_to_user.S b/arch/arm64/lib/copy_to_user.S index 6b99b939c50f..cfdbb1fe8d51 100644 --- a/arch/arm64/lib/copy_to_user.S +++ b/arch/arm64/lib/copy_to_user.S @@ -42,7 +42,7 @@ .endm .macro strh1 ptr, regB, val - uao_user_alternative 9998f, strh, sttrh, \ptr, \regB, \val + uao_user_alternative 9997f, strh, sttrh, \ptr, \regB, \val .endm .macro ldr1 ptr, regB, val @@ -50,7 +50,7 @@ .endm .macro str1 ptr, regB, val - uao_user_alternative 9998f, str, sttr, \ptr, \regB, \val + uao_user_alternative 9997f, str, sttr, \ptr, \regB, \val .endm .macro ldp1 ptr, regB, regC, val @@ -58,13 +58,15 @@ .endm .macro stp1 ptr, regB, regC, val - uao_stp 9998f, \ptr, \regB, \regC, \val + uao_stp 9997f, \ptr, \regB, \regC, \val .endm end .req x5 +srcin .req x15 ENTRY(__arch_copy_to_user) uaccess_enable_not_uao x3, x4, x5 add end, x0, x2 + mov srcin, x1 #include "copy_template.S" uaccess_disable_not_uao x3, x4 mov x0, #0 @@ -73,6 +75,12 @@ ENDPROC(__arch_copy_to_user) .section .fixup,"ax" .align 2 +9997: cmp dst, dstin + b.ne 9998f + // Before being absolutely sure we couldn't copy anything, try harder + ldrb tmp1w, [srcin] +USER(9998f, sttrb tmp1w, [dst]) + add dst, dst, #1 9998: sub x0, end, dst // bytes not copied uaccess_disable_not_uao x3, x4 ret