From mboxrd@z Thu Jan 1 00:00:00 1970 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 94F66C433EF for ; Sat, 25 Dec 2021 02:05:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231801AbhLYCFV (ORCPT ); Fri, 24 Dec 2021 21:05:21 -0500 Received: from szxga01-in.huawei.com ([45.249.212.187]:33911 "EHLO szxga01-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229539AbhLYCFU (ORCPT ); Fri, 24 Dec 2021 21:05:20 -0500 Received: from dggpemm500020.china.huawei.com (unknown [172.30.72.55]) by szxga01-in.huawei.com (SkyGuard) with ESMTP id 4JLS1J6R83zcbrD; Sat, 25 Dec 2021 10:04:52 +0800 (CST) Received: from dggpemm500001.china.huawei.com (7.185.36.107) by dggpemm500020.china.huawei.com (7.185.36.49) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Sat, 25 Dec 2021 10:05:18 +0800 Received: from [10.174.177.243] (10.174.177.243) by dggpemm500001.china.huawei.com (7.185.36.107) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256) id 15.1.2308.20; Sat, 25 Dec 2021 10:05:17 +0800 Message-ID: Date: Sat, 25 Dec 2021 10:05:16 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.2.0 Subject: Re: [PATCH] Revert "mm/usercopy: Drop extra is_vmalloc_or_module() check" Content-Language: en-US To: Christophe Leroy , Kees Cook , Laura Abbott , Mark Rutland , "linux-mm@kvack.org" , "Andrew Morton" , "linux-kernel@vger.kernel.org" , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , "linuxppc-dev@lists.ozlabs.org" , Nick Piggin References: <20211223102126.161848-1-wangkefeng.wang@huawei.com> <96fe1826-aeaf-4ea0-9f01-03d6b3933b34@huawei.com> <6e2ddc83-bec3-fdd4-4d91-3ade0de0b7c8@csgroup.eu> From: Kefeng Wang In-Reply-To: <6e2ddc83-bec3-fdd4-4d91-3ade0de0b7c8@csgroup.eu> Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 8bit X-Originating-IP: [10.174.177.243] X-ClientProxiedBy: dggeme706-chm.china.huawei.com (10.1.199.102) To dggpemm500001.china.huawei.com (7.185.36.107) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/12/24 21:18, Christophe Leroy wrote: > > Le 24/12/2021 à 08:06, Kefeng Wang a écrit : >> On 2021/12/24 14:01, Christophe Leroy wrote: >>> Le 23/12/2021 à 11:21, Kefeng Wang a écrit : >>>> This reverts commit 517e1fbeb65f5eade8d14f46ac365db6c75aea9b. >>>> >>>>     usercopy: Kernel memory exposure attempt detected from SLUB >>>> object not in SLUB page?! (offset 0, size 1048)! >>>>     kernel BUG at mm/usercopy.c:99 >>>>     ... >>>>     usercopy_abort+0x64/0xa0 (unreliable) >>>>     __check_heap_object+0x168/0x190 >>>>     __check_object_size+0x1a0/0x200 >>>>     dev_ethtool+0x2494/0x2b20 >>>>     dev_ioctl+0x5d0/0x770 >>>>     sock_do_ioctl+0xf0/0x1d0 >>>>     sock_ioctl+0x3ec/0x5a0 >>>>     __se_sys_ioctl+0xf0/0x160 >>>>     system_call_exception+0xfc/0x1f0 >>>>     system_call_common+0xf8/0x200 >>>> >>>> When run ethtool eth0, the BUG occurred, the code shows below, >>>> >>>>     data = vzalloc(array_size(gstrings.len, ETH_GSTRING_LEN)); >>>>     copy_to_user(useraddr, data, gstrings.len * ETH_GSTRING_LEN)) >>>> >>>> The data is alloced by vmalloc(),  virt_addr_valid(ptr) will return true >>>> on PowerPC64, which leads to the panic, add back the >>>> is_vmalloc_or_module() >>>> check to fix it. >>> Is it expected that virt_addr_valid() returns true on PPC64 for >>> vmalloc'ed memory ? If that's the case it also means that >>> CONFIG_DEBUG_VIRTUAL won't work as expected either. >> Our product reports this bug to me, after let them do some test, >> >> I found virt_addr_valid return true for vmalloc'ed memory on their board. >> >> I think DEBUG_VIRTUAL could not be work well too, but I can't test it. >> >>> If it is unexpected, I think you should fix PPC64 instead of adding this >>> hack back. Maybe the ARM64 fix can be used as a starting point, see >>> commit 68dd8ef32162 ("arm64: memory: Fix virt_addr_valid() using >>> __is_lm_address()") >> Yes， I check the history,  fix virt_addr_valid() on PowerPC is what I >> firstly want to do, >> >> but I am not familiar with PPC, and also HARDENED_USERCOPY on other's >> ARCHs could >> >> has this issue too, so I add the workaround back. >> >> >> 1) PPC maintainer/expert, any suggestion ? >> >> 2) Maybe we could add some check to WARN this scenario. >> >> --- a/mm/usercopy.c >> +++ b/mm/usercopy.c >> @@ -229,6 +229,8 @@ static inline void check_heap_object(const void >> *ptr, unsigned long n, >>         if (!virt_addr_valid(ptr)) >>                 return; >> >> +       WARN_ON_ONCE(is_vmalloc_or_module_addr(ptr)); >> >>> In the meantime, can you provide more information on your config, >>> especially which memory model is used ? >> Some useful configs, >> >> CONFIG_PPC64=y >> CONFIG_PPC_BOOK3E_64=y >> CONFIG_E5500_CPU=y >> CONFIG_TARGET_CPU_BOOL=y >> CONFIG_PPC_BOOK3E=y >> CONFIG_E500=y >> CONFIG_PPC_E500MC=y >> CONFIG_PPC_FPU=y >> CONFIG_FSL_EMB_PERFMON=y >> CONFIG_FSL_EMB_PERF_EVENT=y >> CONFIG_FSL_EMB_PERF_EVENT_E500=y >> CONFIG_BOOKE=y >> CONFIG_PPC_FSL_BOOK3E=y >> CONFIG_PTE_64BIT=y >> CONFIG_PHYS_64BIT=y >> CONFIG_PPC_MMU_NOHASH=y >> CONFIG_PPC_BOOK3E_MMU=y >> CONFIG_SELECT_MEMORY_MODEL=y >> CONFIG_FLATMEM_MANUAL=y >> CONFIG_FLATMEM=y >> CONFIG_FLAT_NODE_MEM_MAP=y >> CONFIG_SPARSEMEM_VMEMMAP_ENABLE=y >> > OK so it is PPC64 book3e and with flatmem. > > The problem is virt_to_pfn() which uses __pa() > > __pa(x) on PPC64 is (x) & 0x0fffffffffffffffUL > > And on book3e/64 we have > > VMALLOC_START = KERN_VIRT_START = ASM_CONST(0x8000000000000000) > > > It means that __pa() will return a valid PFN for VMALLOCed addresses. > > > So an additional check is required in virt_addr_valid(), maybe check > that (kaddr & PAGE_OFFSET) == PAGE_OFFSET > > Can you try that ? > > #define virt_addr_valid(kaddr) ((kaddr & PAGE_OFFSET) == PAGE_OFFSET && > pfn_valid(virt_to_pfn(kaddr))) I got this commit, commit 4dd7554a6456d124c85e0a4ad156625b71390b5c Author: Nicholas Piggin Date:   Wed Jul 24 18:46:37 2019 +1000     powerpc/64: Add VIRTUAL_BUG_ON checks for __va and __pa addresses     Ensure __va is given a physical address below PAGE_OFFSET, and __pa is     given a virtual address above PAGE_OFFSET. It has check the PAGE_OFFSET in __pa,  will test it and resend the patch(with above warning changes). Thanks. > > > Thanks > Christophe