From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-qk0-f197.google.com (mail-qk0-f197.google.com [209.85.220.197]) by kanga.kvack.org (Postfix) with ESMTP id 7638A6B025E for ; Wed, 21 Sep 2016 01:05:22 -0400 (EDT) Received: by mail-qk0-f197.google.com with SMTP id n185so90690524qke.2 for ; Tue, 20 Sep 2016 22:05:22 -0700 (PDT) Received: from sender153-mail.zoho.com (sender153-mail.zoho.com. [74.201.84.153]) by mx.google.com with ESMTPS id m123si21479952qkf.103.2016.09.20.22.05.21 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Tue, 20 Sep 2016 22:05:21 -0700 (PDT) Subject: Re: [PATCH 2/3] lib/ioremap.c: avoid endless loop under ioremapping improper ranges References: <57E0CE04.2070605@zoho.com> From: zijun_hu Message-ID: <57E214DA.4020304@zoho.com> Date: Wed, 21 Sep 2016 13:04:26 +0800 MIME-Version: 1.0 In-Reply-To: <57E0CE04.2070605@zoho.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: zijun_hu@htc.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org On 09/20/2016 01:49 PM, zijun_hu wrote: > From: zijun_hu > > for ioremap_page_range(), endless loop maybe happen if either of parameter > addr and end is not page aligned, in order to fix this issue and hint range > parameter requirements BUG_ON() checkup are performed firstly > > for ioremap_pte_range(), loop end condition is optimized due to lack of > relevant macro pte_addr_end() > > Signed-off-by: zijun_hu > --- > lib/ioremap.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/lib/ioremap.c b/lib/ioremap.c > index 86c8911..0058cc8 100644 > --- a/lib/ioremap.c > +++ b/lib/ioremap.c > @@ -64,7 +64,7 @@ static int ioremap_pte_range(pmd_t *pmd, unsigned long addr, > BUG_ON(!pte_none(*pte)); > set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot)); > pfn++; > - } while (pte++, addr += PAGE_SIZE, addr != end); > + } while (pte++, addr += PAGE_SIZE, addr < end); > return 0; > } > > @@ -129,6 +129,7 @@ int ioremap_page_range(unsigned long addr, > int err; > > BUG_ON(addr >= end); > + BUG_ON(!PAGE_ALIGNED(addr | end)); > > start = addr; > phys_addr -= addr; > another approach is provided in another mail thread as below i don't known which is more appropriate From: zijun_hu Subject: [PATCH 1/1] lib/ioremap.c: avoid endless loop under ioremapping page unaligned ranges endless loop maybe happen if either of parameter addr and end is not page aligned for kernel API function ioremap_page_range() in order to fix this issue and alert improper range parameters to user WARN_ON() checkup and rounding down range lower boundary are performed firstly, loop end condition within ioremap_pte_range() is optimized due to lack of relevant macro pte_addr_end() Signed-off-by: zijun_hu --- lib/ioremap.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/lib/ioremap.c b/lib/ioremap.c index 86c8911..911bdca 100644 --- a/lib/ioremap.c +++ b/lib/ioremap.c @@ -64,7 +64,7 @@ static int ioremap_pte_range(pmd_t *pmd, unsigned long addr, BUG_ON(!pte_none(*pte)); set_pte_at(&init_mm, addr, pte, pfn_pte(pfn, prot)); pfn++; - } while (pte++, addr += PAGE_SIZE, addr != end); + } while (pte++, addr += PAGE_SIZE, addr < end && addr >= PAGE_SIZE); return 0; } @@ -129,7 +129,9 @@ int ioremap_page_range(unsigned long addr, int err; BUG_ON(addr >= end); + WARN_ON(!PAGE_ALIGNED(addr) || !PAGE_ALIGNED(end)); + addr = round_down(addr, PAGE_SIZE); start = addr; phys_addr -= addr; pgd = pgd_offset_k(addr); -- 1.9.1 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org