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[156.151.31.86]) by mx.google.com with ESMTPS id s35si31297579pgl.277.2019.04.09.20.40.47 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 09 Apr 2019 20:40:47 -0700 (PDT) Received-SPF: pass (google.com: domain of mike.kravetz@oracle.com designates 156.151.31.86 as permitted sender) client-ip=156.151.31.86; Authentication-Results: mx.google.com; dkim=pass header.i=@oracle.com header.s=corp-2018-07-02 header.b=rRwR4Bkd; spf=pass (google.com: domain of mike.kravetz@oracle.com designates 156.151.31.86 as permitted sender) smtp.mailfrom=mike.kravetz@oracle.com; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=oracle.com Received: from pps.filterd (userp2130.oracle.com [127.0.0.1]) by userp2130.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x3A3dC83154840; Wed, 10 Apr 2019 03:40:39 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=subject : to : cc : references : from : message-id : date : mime-version : in-reply-to : content-type : content-transfer-encoding; s=corp-2018-07-02; bh=Se3eqjiQ+KjWFbu2w1/InnBHreZHz/aMu1Zqi27aT5o=; b=rRwR4Bkdlj03ex4ljsKrGUzX0uHeWROPAfoqLLE1tCG6auKbQeGA5ByMe7J6hWwul3Bt kNNb4/BaQISVrxnLIWE/DQDqD6h3GVSlDnx1aFRpJoJwyet9RIn40JiafxuJGJoZUgEq nDti0eosOLbu6563lBtoC2gb1t4PlWzZRWoe47FayV0NHepCsgQEj0DfU+/Ymgkmayb7 +ouQUqSXadVHsfv4e9y3WZ4fQjHERCBf0k4iUv60zpFpJlu5svwXbP+VWYt8GRiOxroQ 0hOCWzFy/GqxzIKDAF5jH+cwP+EgMr8uFXqGY0EgSaTsbcU1UP1MV3fugQg/skRY9Q7e Bw== Received: from userp3020.oracle.com (userp3020.oracle.com [156.151.31.79]) by userp2130.oracle.com with ESMTP id 2rpkht0kf5-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 10 Apr 2019 03:40:38 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.27/8.16.0.27) with SMTP id x3A3bx2V050047; Wed, 10 Apr 2019 03:38:38 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3020.oracle.com with ESMTP id 2rpkejn6mk-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 10 Apr 2019 03:38:38 +0000 Received: from abhmp0007.oracle.com (abhmp0007.oracle.com [141.146.116.13]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id x3A3caPP011490; Wed, 10 Apr 2019 03:38:36 GMT Received: from [192.168.1.222] (/50.38.38.67) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Tue, 09 Apr 2019 20:38:36 -0700 Subject: Re: [PATCH] hugetlbfs: fix protential null pointer dereference To: Yufen Yu , linux-mm@kvack.org Cc: kirill.shutemov@linux.intel.com, n-horiguchi@ah.jp.nec.com, mhocko@kernel.org References: <20190410025037.144872-1-yuyufen@huawei.com> From: Mike Kravetz Message-ID: Date: Tue, 9 Apr 2019 20:38:35 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: <20190410025037.144872-1-yuyufen@huawei.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9222 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904100025 X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9222 signatures=668685 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1904100026 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 4/9/19 7:50 PM, Yufen Yu wrote: > After commit 58b6e5e8f1ad ("hugetlbfs: fix memory leak for resv_map"), > i_mapping->private_data will be NULL for mode that is not regular and link. > Then, it might cause NULL pointer derefernce in hugetlb_reserve_pages() > when do_mmap. We can avoid protential null pointer dereference by > judging whether it have been allocated. > > Fixes: 58b6e5e8f1ad ("hugetlbfs: fix memory leak for resv_map") > Cc: Kirill A. Shutemov > Cc: Naoya Horiguchi > Cc: Michal Hocko > Signed-off-by: Yufen Yu Thanks for catching this. I mistakenly thought all the code was checking for NULL resv_map. That certainly is one (and only) place where it is not checked. Have you verified that this is possible? Should be pretty easy to do. If you have not, I can try to verify tomorrow. > --- > mm/hugetlb.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/mm/hugetlb.c b/mm/hugetlb.c > index 97b1e0290c66..15e4baf2aa7d 100644 > --- a/mm/hugetlb.c > +++ b/mm/hugetlb.c > @@ -4465,6 +4465,8 @@ int hugetlb_reserve_pages(struct inode *inode, > */ > if (!vma || vma->vm_flags & VM_MAYSHARE) { > resv_map = inode_resv_map(inode); > + if (!resv_map) > + return -EOPNOTSUPP; I'm not sure about the return code here. Note that all callers of hugetlb_reserve_pages() force return value of -ENOMEM if non-zero value is returned. I think we would like to return -EACCES in this situation. The mmap man page says: EACCES A file descriptor refers to a non-regular file. Or ... -- Mike Kravetz > > chg = region_chg(resv_map, from, to); > >