From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755944AbcHBVSM (ORCPT ); Tue, 2 Aug 2016 17:18:12 -0400 Received: from sender153-mail.zoho.com ([74.201.84.153]:21995 "EHLO sender153-mail.zoho.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753719AbcHBVSC (ORCPT ); Tue, 2 Aug 2016 17:18:02 -0400 DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=zapps768; d=zoho.com; h=subject:references:cc:from:message-id:date:user-agent:mime-version:in-reply-to:content-type; b=hMxXY5SeQn9zckUxRn4AOu7hFtx3Q0+5I09PVnXdhIsR4mv8BVIntcObvIHvMMValo6OxpHAnY6q vS7jNqhWmogV2g/704HGGQ09tJsQLMmKwFbi1pWqQGQDVO5SYK4I Subject: Re: [PATCH] mm/memblock.c: fix NULL dereference error References: <57A029A9.6060303@zoho.com> 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 From: zijun_hu Message-ID: <57A02DA6.4010501@zoho.com> Date: Tue, 2 Aug 2016 13:20:38 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <57A029A9.6060303@zoho.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit To: unlisted-recipients:; (no To-header on input) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.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--) { >