From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx106.postini.com [74.125.245.106]) by kanga.kvack.org (Postfix) with SMTP id 5C1536B0033 for ; Wed, 24 Jul 2013 00:22:16 -0400 (EDT) Received: from /spool/local by e23smtp02.au.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Wed, 24 Jul 2013 14:11:49 +1000 Received: from d23relay04.au.ibm.com (d23relay04.au.ibm.com [9.190.234.120]) by d23dlp03.au.ibm.com (Postfix) with ESMTP id 7097D3578050 for ; Wed, 24 Jul 2013 14:22:10 +1000 (EST) Received: from d23av03.au.ibm.com (d23av03.au.ibm.com [9.190.234.97]) by d23relay04.au.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id r6O46kac43778184 for ; Wed, 24 Jul 2013 14:06:46 +1000 Received: from d23av03.au.ibm.com (loopback [127.0.0.1]) by d23av03.au.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id r6O4M9tU023648 for ; Wed, 24 Jul 2013 14:22:10 +1000 Date: Wed, 24 Jul 2013 12:22:08 +0800 From: Wanpeng Li Subject: Re: [PATCH] mm: Fix potential NULL pointer dereference Message-ID: <20130724042208.GJ22680@hacker.(null)> Reply-To: Wanpeng Li References: <1374637699-25704-1-git-send-email-huawei.libin@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1374637699-25704-1-git-send-email-huawei.libin@huawei.com> Sender: owner-linux-mm@kvack.org List-ID: To: Libin Cc: linux-mm@kvack.org, akpm@linux-foundation.org, kirill.shutemov@linux.intel.com, mgorman@suse.de, xiaoguangrong@linux.vnet.ibm.com, wujianguo@huawei.com On Wed, Jul 24, 2013 at 11:48:19AM +0800, Libin wrote: >find_vma may return NULL, thus check the return >value to avoid NULL pointer dereference. > When can this happen since down_read(&mm->mmap_sem) is held? >Signed-off-by: Libin >--- > mm/huge_memory.c | 2 ++ > 1 file changed, 2 insertions(+) > >diff --git a/mm/huge_memory.c b/mm/huge_memory.c >index 243e710..d4423f4 100644 >--- a/mm/huge_memory.c >+++ b/mm/huge_memory.c >@@ -2294,6 +2294,8 @@ static void collapse_huge_page(struct mm_struct *mm, > goto out; > > vma = find_vma(mm, address); >+ if (!vma) >+ goto out; > hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK; > hend = vma->vm_end & HPAGE_PMD_MASK; > if (address < hstart || address + HPAGE_PMD_SIZE > hend) >-- >1.8.2.1 > > >-- >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 -- 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