Patch "md: Fix overflow in is_mddev_idle" has been added to the 6.1-stable tree

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This is a note to let you know that I've just added the patch titled

    md: Fix overflow in is_mddev_idle

to the 6.1-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     md-fix-overflow-in-is_mddev_idle.patch
and it can be found in the queue-6.1 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit 6338df4eea90a285832af592547f2b04b667d019
Author: Li Nan <linan122@xxxxxxxxxx>
Date:   Wed Jan 17 11:19:45 2024 +0800

    md: Fix overflow in is_mddev_idle
    
    [ Upstream commit 3f9f231236ce7e48780d8a4f1f8cb9fae2df1e4e ]
    
    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@xxxxxxxxxx>
    Reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>
    Link: https://lore.kernel.org/r/20240117031946.2324519-2-linan666@xxxxxxxxxxxxxxx
    Signed-off-by: Song Liu <song@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 506c998c0ca59..3d2befb0baf46 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -8542,14 +8542,15 @@ 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.
diff --git a/drivers/md/md.h b/drivers/md/md.h
index 4f0b480974552..5910527514db2 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 */
+	long long last_events;		/* IO event timestamp */
 
 	/*
 	 * If meta_bdev is non-NULL, it means that a separate device is
@@ -576,7 +576,7 @@ 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/blkdev.h b/include/linux/blkdev.h
index e255674a9ee72..02e55676e0283 100644
--- a/include/linux/blkdev.h
+++ b/include/linux/blkdev.h
@@ -161,7 +161,7 @@ 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;




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