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md: Fix overflow in is_mddev_idle

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UBSAN reports this problem:

  UBSAN: Undefined behaviour in drivers/md/md.c:8175:15
  signed integer overflow:
  -2147483291 - 2072033152 cannot be represented in type 'int'
  Call trace:
   dump_backtrace+0x0/0x310
   show_stack+0x28/0x38
   dump_stack+0xec/0x15c
   ubsan_epilogue+0x18/0x84
   handle_overflow+0x14c/0x19c
   __ubsan_handle_sub_overflow+0x34/0x44
   is_mddev_idle+0x338/0x3d8
   md_do_sync+0x1bb8/0x1cf8
   md_thread+0x220/0x288
   kthread+0x1d8/0x1e0
   ret_from_fork+0x10/0x18

'curr_events' will overflow when stat accum or 'sync_io' is greater than
INT_MAX.

Fix it by changing sync_io, last_events and curr_events to 64bit.

Signed-off-by: Li Nan <linan122@huawei.com>
Reviewed-by: Yu Kuai <yukuai3@huawei.com>
Link: https://lore.kernel.org/r/20240117031946.2324519-2-linan666@huaweicloud.com
Signed-off-by: Song Liu <song@kernel.org>
This commit is contained in:
Li Nan 2024-01-17 11:19:45 +08:00 committed by Song Liu
parent 3821bbad0d
commit 3f9f231236
3 changed files with 7 additions and 6 deletions
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7
drivers/md/md.c
View File

@ -8577,14 +8577,15 @@ 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_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);
/* 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.

4
drivers/md/md.h
View File

@ -51,7 +51,7 @@ 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
@ -621,7 +621,7 @@ 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)

2
include/linux/blkdev.h
View File

@ -172,7 +172,7 @@ 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_ZONED