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 5C99FC433EF for ; Wed, 19 Jan 2022 09:55:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240083AbiASJzZ (ORCPT ); Wed, 19 Jan 2022 04:55:25 -0500 Received: from foss.arm.com ([217.140.110.172]:52016 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240064AbiASJzY (ORCPT ); Wed, 19 Jan 2022 04:55:24 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 89B491FB; Wed, 19 Jan 2022 01:55:23 -0800 (PST) Received: from C02TD0UTHF1T.local (unknown [10.57.38.123]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id B5C253F766; Wed, 19 Jan 2022 01:55:21 -0800 (PST) Date: Wed, 19 Jan 2022 09:55:14 +0000 From: Mark Rutland To: Yury Norov Cc: Catalin Marinas , Will Deacon , Andrew Morton , Nicholas Piggin , Ding Tianhong , Anshuman Khandual , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [RFC PATCH] arm64: don't vmap() invalid page Message-ID: <20220119095514.GA42995@C02TD0UTHF1T.local> References: <20220118185354.464517-1-yury.norov@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220118185354.464517-1-yury.norov@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 18, 2022 at 10:53:54AM -0800, Yury Norov wrote: > vmap() takes struct page *pages as one of arguments, and user may provide > an invalid pointer, which would lead to DABT at address translation later. > Currently, kernel checks the pages against NULL. In my case, however, the > address was not NULL, and was big enough so that the hardware generated > Address Size Abort. Can you give an example of when this might happen? It sounds like you're actually hitting this, so a backtrace would be nice. I'm a bit confused as to when why we'd try to vmap() pages that we didn't have a legitimate struct page for -- where did these addresses come from? It sounds like this is going wrong at a higher level, and we're passing entirely bogus struct page pointers around. This seems like the sort of thing DEBUG_VIRTUAL or similar should check when we initially generate the struct page pointer. Thanks, Mark. > Interestingly, this abort happens even if copy_from_kernel_nofault() is used, > which is quite inconvenient for debugging purposes. > > This patch adds an arch_vmap_page_valid() helper into vmap() path, so that > architectures may add arch-specific checks of the pointer passed into vmap. > > For arm64, if the page passed to vmap() corresponds to a physical address > greater than maximum possible value as described in TCR_EL1.IPS register, the > following table walk would generate Address Size Abort. Instead of creating > the invalid mapping, kernel will return ERANGE in such situation. > > Signed-off-by: Yury Norov > --- > arch/arm64/include/asm/vmalloc.h | 41 ++++++++++++++++++++++++++++++++ > include/linux/vmalloc.h | 7 ++++++ > mm/vmalloc.c | 8 +++++-- > 3 files changed, 54 insertions(+), 2 deletions(-) > > diff --git a/arch/arm64/include/asm/vmalloc.h b/arch/arm64/include/asm/vmalloc.h > index b9185503feae..e9d43ee019ad 100644 > --- a/arch/arm64/include/asm/vmalloc.h > +++ b/arch/arm64/include/asm/vmalloc.h > @@ -4,6 +4,47 @@ > #include > #include > > +static inline u64 pa_size(u64 ips) > +{ > + switch (ips) { > + case 0b000: > + return 1UL << 32; > + case 0b001: > + return 1UL << 36; > + case 0b010: > + return 1UL << 40; > + case 0b011: > + return 1UL << 42; > + case 0b100: > + return 1UL << 44; > + case 0b101: > + return 1UL << 48; > + case 0b110: > + return 1UL << 52; > + /* All other values */ > + default: > + return 1UL << 52; > + } > +} > + > +#define arch_vmap_page_valid arch_vmap_page_valid > +static inline int arch_vmap_page_valid(struct page *page) > +{ > + u64 tcr, ips, paddr_size; > + > + if (!page) > + return -ENOMEM; > + > + tcr = read_sysreg_s(SYS_TCR_EL1); > + ips = (tcr & TCR_IPS_MASK) >> TCR_IPS_SHIFT; > + > + paddr_size = pa_size(ips); > + if (page_to_phys(page) >= paddr_size) > + return -ERANGE; > + > + return 0; > +} > + > #ifdef CONFIG_HAVE_ARCH_HUGE_VMAP > > #define arch_vmap_pud_supported arch_vmap_pud_supported > diff --git a/include/linux/vmalloc.h b/include/linux/vmalloc.h > index 6e022cc712e6..08b567d8bafc 100644 > --- a/include/linux/vmalloc.h > +++ b/include/linux/vmalloc.h > @@ -119,6 +119,13 @@ static inline int arch_vmap_pte_supported_shift(unsigned long size) > } > #endif > > +#ifndef arch_vmap_page_valid > +static inline int arch_vmap_page_valid(struct page *page) > +{ > + return page ? 0 : -ENOMEM; > +} > +#endif > + > /* > * Highlevel APIs for driver use > */ > diff --git a/mm/vmalloc.c b/mm/vmalloc.c > index d2a00ad4e1dd..ee0384405cdd 100644 > --- a/mm/vmalloc.c > +++ b/mm/vmalloc.c > @@ -472,11 +472,15 @@ static int vmap_pages_pte_range(pmd_t *pmd, unsigned long addr, > return -ENOMEM; > do { > struct page *page = pages[*nr]; > + int ret; > > if (WARN_ON(!pte_none(*pte))) > return -EBUSY; > - if (WARN_ON(!page)) > - return -ENOMEM; > + > + ret = arch_vmap_page_valid(page); > + if (WARN_ON(ret)) > + return ret; > + > set_pte_at(&init_mm, addr, pte, mk_pte(page, prot)); > (*nr)++; > } while (pte++, addr += PAGE_SIZE, addr != end); > -- > 2.30.2 >