From patchwork Fri Dec 10 12:06:29 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Li Jinlin X-Patchwork-Id: 12669453 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 29DE7C433EF for ; Fri, 10 Dec 2021 11:35:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240607AbhLJLjN (ORCPT ); Fri, 10 Dec 2021 06:39:13 -0500 Received: from szxga02-in.huawei.com ([45.249.212.188]:28305 "EHLO szxga02-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235378AbhLJLjM (ORCPT ); Fri, 10 Dec 2021 06:39:12 -0500 Received: from canpemm500008.china.huawei.com (unknown [172.30.72.55]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4J9TNS6ZRFzbk9Z; Fri, 10 Dec 2021 19:35:20 +0800 (CST) Received: from localhost.huawei.com (10.175.124.27) by canpemm500008.china.huawei.com (7.192.105.151) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.20; Fri, 10 Dec 2021 19:35:34 +0800 From: Li Jinlin To: , , , , , , , , CC: , , , Subject: [PATCH v3 1/3] md: Fix undefined behaviour in is_mddev_idle Date: Fri, 10 Dec 2021 20:06:29 +0800 Message-ID: <20211210120631.2578505-2-lijinlin3@huawei.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20211210120631.2578505-1-lijinlin3@huawei.com> References: <20211210120631.2578505-1-lijinlin3@huawei.com> MIME-Version: 1.0 X-Originating-IP: [10.175.124.27] X-ClientProxiedBy: dggems705-chm.china.huawei.com (10.3.19.182) To canpemm500008.china.huawei.com (7.192.105.151) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org UBSAN reports this problem: [ 5984.281385] UBSAN: Undefined behaviour in drivers/md/md.c:8175:15 [ 5984.281390] signed integer overflow: [ 5984.281393] -2147483291 - 2072033152 cannot be represented in type 'int' [ 5984.281400] CPU: 25 PID: 1854 Comm: md101_resync Kdump: loaded Not tainted 4.19.90 [ 5984.281404] Hardware name: Huawei TaiShan 200 (Model 5280)/BC82AMDDA [ 5984.281406] Call trace: [ 5984.281415] dump_backtrace+0x0/0x310 [ 5984.281418] show_stack+0x28/0x38 [ 5984.281425] dump_stack+0xec/0x15c [ 5984.281430] ubsan_epilogue+0x18/0x84 [ 5984.281434] handle_overflow+0x14c/0x19c [ 5984.281439] __ubsan_handle_sub_overflow+0x34/0x44 [ 5984.281445] is_mddev_idle+0x338/0x3d8 [ 5984.281449] md_do_sync+0x1bb8/0x1cf8 [ 5984.281452] md_thread+0x220/0x288 [ 5984.281457] kthread+0x1d8/0x1e0 [ 5984.281461] ret_from_fork+0x10/0x18 When the stat aacum of the disk is greater than INT_MAX, its value becomes negative after casting to 'int', which may lead to overflow after subtracting a positive number. In the same way, when the value of sync_io is greater than INT_MAX, overflow may also occur. These situations will lead to undefined behavior. Otherwise, if the stat accum of the disk is close to INT_MAX when creating raid arrays, the initial value of last_events would be set close to INT_MAX when mddev initializes IO event counters. 'curr_events - rdev->last_events > 64' will always false during synchronization. If all the disks of mddev are in this case, is_mddev_idle() will always return 1, which may cause non-sync IO is very slow. Fix by using atomic64_t type for sync_io, and using s64 type for curr_events/last_events. Signed-off-by: Li Jinlin --- drivers/md/md.c | 6 +++--- drivers/md/md.h | 4 ++-- include/linux/genhd.h | 2 +- 3 files changed, 6 insertions(+), 6 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 5111ed966947..be73a5ae6864 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8429,14 +8429,14 @@ static int is_mddev_idle(struct mddev *mddev, int init) { struct md_rdev *rdev; int idle; - int curr_events; + s64 curr_events; idle = 1; rcu_read_lock(); rdev_for_each_rcu(rdev, mddev) { struct gendisk *disk = rdev->bdev->bd_disk; - curr_events = (int)part_stat_read_accum(disk->part0, sectors) - - atomic_read(&disk->sync_io); + curr_events = (s64)part_stat_read_accum(disk->part0, sectors) - + atomic64_read(&disk->sync_io); /* sync IO will cause sync_io to increase before the disk_stats * as sync_io is counted when a request starts, and * disk_stats is counted when it completes. diff --git a/drivers/md/md.h b/drivers/md/md.h index 53ea7a6961de..e00d6730da13 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -50,7 +50,7 @@ struct md_rdev { sector_t sectors; /* Device size (in 512bytes sectors) */ struct mddev *mddev; /* RAID array if running */ - int last_events; /* IO event timestamp */ + s64 last_events; /* IO event timestamp */ /* * If meta_bdev is non-NULL, it means that a separate device is @@ -551,7 +551,7 @@ extern void mddev_unlock(struct mddev *mddev); static inline void md_sync_acct(struct block_device *bdev, unsigned long nr_sectors) { - atomic_add(nr_sectors, &bdev->bd_disk->sync_io); + atomic64_add(nr_sectors, &bdev->bd_disk->sync_io); } static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors) diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 74c410263113..efa7884de11b 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -150,7 +150,7 @@ struct gendisk { struct list_head slave_bdevs; #endif struct timer_rand_state *random; - atomic_t sync_io; /* RAID */ + atomic64_t sync_io; /* RAID */ struct disk_events *ev; #ifdef CONFIG_BLK_DEV_INTEGRITY struct kobject integrity_kobj;