From patchwork Thu Mar 4 06:21:26 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ritesh Harjani X-Patchwork-Id: 12115549 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-16.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B7B8EC433DB for ; Thu, 4 Mar 2021 06:23:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 7AACF64EDF for ; Thu, 4 Mar 2021 06:23:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235079AbhCDGWt (ORCPT ); Thu, 4 Mar 2021 01:22:49 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:4062 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234859AbhCDGWa (ORCPT ); Thu, 4 Mar 2021 01:22:30 -0500 Received: from pps.filterd (m0098393.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 12464ApJ002003; Thu, 4 Mar 2021 01:21:49 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : date : message-id : mime-version : content-transfer-encoding; s=pp1; bh=C/UEZBuZ9fJJJjUOHrXxdlo2KGgCtmOmAhhi4GZjqCc=; b=ETbxTAUwAH7uDT5rvPYB+0e4r5hFEWCOan8oowg79DqeDGOM+D3upCsLOHzN0LkBkEHS F8gjQBi4qL5Tr34pQ8T72LwqktYDvo0MB1qQ91RVkywPP59cKp964OT79UBFlafuB8dx lbtHlF18OABqXZoqKEMT/UB8Oyrt7xsYWOONkwQWuXbaiBzusWnN2y3TdCu7gVz2JrNi eT1uW4I+O3nNfp2+p3X4+vfMM/d+4Ro3eFDRG2OA7obakNhqs99bJMQtUa1+DgYkZEnf zW4oZKrBQJ1YwEvfmNwXuCu8H42JsPCOsXelFwtxKyko12GCDX4RFOCOhFZ3bfulMg9U MA== Received: from ppma03fra.de.ibm.com (6b.4a.5195.ip4.static.sl-reverse.com [149.81.74.107]) by mx0a-001b2d01.pphosted.com with ESMTP id 372squs1r6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 04 Mar 2021 01:21:49 -0500 Received: from pps.filterd (ppma03fra.de.ibm.com [127.0.0.1]) by ppma03fra.de.ibm.com (8.16.0.42/8.16.0.42) with SMTP id 1246IrUs021627; Thu, 4 Mar 2021 06:21:47 GMT Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by ppma03fra.de.ibm.com with ESMTP id 371a8es4u6-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 04 Mar 2021 06:21:47 +0000 Received: from d06av23.portsmouth.uk.ibm.com (d06av23.portsmouth.uk.ibm.com [9.149.105.59]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 1246LjS036766176 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Thu, 4 Mar 2021 06:21:45 GMT Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 13ADBA4057; Thu, 4 Mar 2021 06:21:45 +0000 (GMT) Received: from d06av23.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 0D8D2A4051; Thu, 4 Mar 2021 06:21:44 +0000 (GMT) Received: from riteshh-domain.ibmuc.com (unknown [9.199.35.80]) by d06av23.portsmouth.uk.ibm.com (Postfix) with ESMTP; Thu, 4 Mar 2021 06:21:43 +0000 (GMT) From: Ritesh Harjani To: linux-xfs@vger.kernel.org, linux-ext4@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, anju@linux.vnet.ibm.com, Ritesh Harjani Subject: [PATCH] iomap: Fix negative assignment to unsigned sis->pages in iomap_swapfile_activate Date: Thu, 4 Mar 2021 11:51:26 +0530 Message-Id: X-Mailer: git-send-email 2.26.2 MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.369,18.0.761 definitions=2021-03-04_01:2021-03-03,2021-03-04 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 mlxscore=0 phishscore=0 adultscore=0 priorityscore=1501 clxscore=1011 suspectscore=0 spamscore=0 mlxlogscore=999 bulkscore=0 lowpriorityscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2009150000 definitions=main-2103040025 Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org In case if isi.nr_pages is 0, we are making sis->pages (which is unsigned int) a huge value in iomap_swapfile_activate() by assigning -1. This could cause a kernel crash in kernel v4.18 (with below signature). Or could lead to unknown issues on latest kernel if the fake big swap gets used. Fix this issue by returning -EINVAL in case of nr_pages is 0, since it is anyway a invalid swapfile. Looks like this issue will be hit when we have pagesize < blocksize type of configuration. I was able to hit the issue in case of a tiny swap file with below test script. https://raw.githubusercontent.com/riteshharjani/LinuxStudy/master/scripts/swap-issue.sh kernel crash analysis on v4.18 ============================== On v4.18 kernel, it causes a kernel panic, since sis->pages becomes a huge value and isi.nr_extents is 0. When 0 is returned it is considered as a swapfile over NFS and SWP_FILE is set (sis->flags |= SWP_FILE). Then when swapoff was getting called it was calling a_ops->swap_deactivate() if (sis->flags & SWP_FILE) is true. Since a_ops->swap_deactivate() is NULL in case of XFS, it causes below panic. Panic signature on v4.18 kernel: ======================================= root@qemu:/home/qemu# [ 8291.723351] XFS (loop2): Unmounting Filesystem [ 8292.123104] XFS (loop2): Mounting V5 Filesystem [ 8292.132451] XFS (loop2): Ending clean mount [ 8292.263362] Adding 4294967232k swap on /mnt1/test/swapfile. Priority:-2 extents:1 across:274877906880k [ 8292.277834] Unable to handle kernel paging request for instruction fetch [ 8292.278677] Faulting instruction address: 0x00000000 cpu 0x19: Vector: 400 (Instruction Access) at [c0000009dd5b7ad0] pc: 0000000000000000 lr: c0000000003eb9dc: destroy_swap_extents+0xfc/0x120 sp: c0000009dd5b7d50 msr: 8000000040009033 current = 0xc0000009b6710080 paca = 0xc00000003ffcb280 irqmask: 0x03 irq_happened: 0x01 pid = 5604, comm = swapoff Linux version 4.18.0 (riteshh@xxxxxxx) (gcc version 8.4.0 (Ubuntu 8.4.0-1ubuntu1~18.04)) #57 SMP Wed Mar 3 01:33:04 CST 2021 enter ? for help [link register ] c0000000003eb9dc destroy_swap_extents+0xfc/0x120 [c0000009dd5b7d50] c0000000025a7058 proc_poll_event+0x0/0x4 (unreliable) [c0000009dd5b7da0] c0000000003f0498 sys_swapoff+0x3f8/0x910 [c0000009dd5b7e30] c00000000000bbe4 system_call+0x5c/0x70 --- Exception: c01 (System Call) at 00007ffff7d208d8 Signed-off-by: Ritesh Harjani --- fs/iomap/swapfile.c | 9 +++++++++ 1 file changed, 9 insertions(+) -- 2.26.2 diff --git a/fs/iomap/swapfile.c b/fs/iomap/swapfile.c index a648dbf6991e..67953678c99f 100644 --- a/fs/iomap/swapfile.c +++ b/fs/iomap/swapfile.c @@ -170,6 +170,15 @@ int iomap_swapfile_activate(struct swap_info_struct *sis, return ret; } + /* + * In case if nr_pages is 0 then we better return -EINVAL + * since it is anyway an empty swapfile. + */ + if (isi.nr_pages == 0) { + pr_warn("swapon: Empty swap-file\n"); + return -EINVAL; + } + *pagespan = 1 + isi.highest_ppage - isi.lowest_ppage; sis->max = isi.nr_pages; sis->pages = isi.nr_pages - 1;