From: zhangwensheng <zhangwensheng5(a)huawei.com>
hulk inclusion
category: bugfix
bugzilla: 185891
CVE: NA
--------------------------------
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(a)huawei.com>
Reviewed-by: Hou Tao <houtao1(a)huawei.com>
Signed-off-by: Yang Yingliang <yangyingliang(a)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;
--
2.25.1