From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f72.google.com (mail-pa0-f72.google.com [209.85.220.72]) by kanga.kvack.org (Postfix) with ESMTP id 2D1EB6B025E for ; Tue, 2 Aug 2016 01:23:37 -0400 (EDT) Received: by mail-pa0-f72.google.com with SMTP id pp5so281681033pac.3 for ; Mon, 01 Aug 2016 22:23:37 -0700 (PDT) Received: from sender153-mail.zoho.com (sender153-mail.zoho.com. [74.201.84.153]) by mx.google.com with ESMTPS id gc6si1184453pab.18.2016.08.01.22.23.36 for (version=TLS1 cipher=ECDHE-RSA-AES128-SHA bits=128/128); Mon, 01 Aug 2016 22:23:36 -0700 (PDT) Subject: Re: [PATCH] mm/memblock.c: fix NULL dereference error References: <57A029A9.6060303@zoho.com> From: zijun_hu Message-ID: <57A02DA6.4010501@zoho.com> Date: Tue, 2 Aug 2016 13:20:38 +0800 MIME-Version: 1.0 In-Reply-To: <57A029A9.6060303@zoho.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: Cc: zijun_hu@htc.com, kuleshovmail@gmail.com, tangchen@cn.fujitsu.com, tj@kernel.org, weiyang@linux.vnet.ibm.com, mm-commits@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, torvalds@linux-foundation.org On 08/02/2016 01:03 PM, zijun_hu wrote: > Hi Andrew, > > this patch is part of https://lkml.org/lkml/2016/7/26/347 and isn't merged in > as you advised in another mail, i release this patch against linus's mainline > for fixing relevant bugs completely, see test patch attached for verification > details > >>>From 5a74cb46b7754a45428ff95f4653ad27025c3131 Mon Sep 17 00:00:00 2001 > From: zijun_hu > Date: Tue, 2 Aug 2016 12:35:28 +0800 > Subject: [PATCH] mm/memblock.c: fix NULL dereference error > > it causes NULL dereference error and failure to get type_a->regions[0] info > if parameter type_b of __next_mem_range_rev() == NULL > > the bugs are fixed by checking before dereferring and initializing idx_b > to 0 > > the approach is tested by dumping all types of region via __memblock_dump_all() > and __next_mem_range_rev() fixed to UART separately, the result is okay after > checking the logs > > Signed-off-by: zijun_hu > Tested-by: zijun_hu > Acked-by: Tejun Heo > --- > mm/memblock.c | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/mm/memblock.c b/mm/memblock.c > index ff5ff3b..250dd48 100644 > --- a/mm/memblock.c > +++ b/mm/memblock.c > @@ -994,7 +994,10 @@ void __init_memblock __next_mem_range_rev(u64 *idx, int nid, ulong flags, > > if (*idx == (u64)ULLONG_MAX) { > idx_a = type_a->cnt - 1; > - idx_b = type_b->cnt; > + if (type_b != NULL) > + idx_b = type_b->cnt; > + else > + idx_b = 0; > } > > for (; idx_a >= 0; idx_a--) { > -- 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