From: zhangwensheng zhangwensheng5@huawei.com

hulk inclusion category: bugfix bugzilla: 185891 CVE: NA

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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.

To address these problems, need to use 64bit signed integer type for sync_io,last_events, and curr_events.

Signed-off-by: zhangwensheng zhangwensheng5@huawei.com Reviewed-by: Hou Tao houtao1@huawei.com Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- drivers/md/md.c | 7 ++++--- drivers/md/md.h | 6 +++--- include/linux/genhd.h | 2 +- 3 files changed, 8 insertions(+), 7 deletions(-)

diff --git a/drivers/md/md.c b/drivers/md/md.c index 409ec5ffd28d3..8a68ff71fbbf8 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -8161,14 +8161,15 @@ static int is_mddev_idle(struct mddev *mddev, int init) { struct md_rdev *rdev; int idle; - int curr_events; + long long curr_events;

idle = 1; rcu_read_lock(); rdev_for_each_rcu(rdev, mddev) { struct gendisk *disk = rdev->bdev->bd_contains->bd_disk; - curr_events = (int)part_stat_read_accum(&disk->part0, sectors) - - atomic_read(&disk->sync_io); + curr_events = + (long long)part_stat_read_accum(&disk->part0, sectors) - + atomic64_read(&disk->sync_io_sectors); /* 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 ee3c9768ff9e7..e745f701e1a82 100644 --- a/drivers/md/md.h +++ b/drivers/md/md.h @@ -47,7 +47,7 @@ struct md_rdev {

sector_t sectors; /* Device size (in 512bytes sectors) */ struct mddev *mddev; /* RAID array if running */ - int last_events; /* IO event timestamp */ + long long last_events; /* IO event timestamp */

/* * If meta_bdev is non-NULL, it means that a separate device is @@ -528,12 +528,12 @@ 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_contains->bd_disk->sync_io); + atomic64_add(nr_sectors, &bdev->bd_contains->bd_disk->sync_io_sectors); }

static inline void md_sync_acct_bio(struct bio *bio, unsigned long nr_sectors) { - atomic_add(nr_sectors, &bio->bi_disk->sync_io); + atomic64_add(nr_sectors, &bio->bi_disk->sync_io_sectors); }

struct md_personality diff --git a/include/linux/genhd.h b/include/linux/genhd.h index 9c398294b6279..38737c853b28d 100644 --- a/include/linux/genhd.h +++ b/include/linux/genhd.h @@ -212,7 +212,6 @@ struct gendisk { struct kobject *slave_dir;

struct timer_rand_state *random; - atomic_t sync_io; /* RAID */ struct disk_events *ev; #ifdef CONFIG_BLK_DEV_INTEGRITY struct kobject integrity_kobj; @@ -220,6 +219,7 @@ struct gendisk { int node_id; struct badblocks *bb; struct lockdep_map lockdep_map; + atomic64_t sync_io_sectors; /* RAID */

#ifndef __GENKSYMS__ unsigned long *user_ro_bitmap;