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s390/dasd: Use correct lock while counting channel queue length

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commit ccc45cb4e7 upstream.

The lock around counting the channel queue length in the BIODASDINFO
ioctl was incorrectly changed to the dasd_block->queue_lock with commit
583d6535cb ("dasd: remove dead code"). This can lead to endless list
iterations and a subsequent crash.

The queue_lock is supposed to be used only for queue lists belonging to
dasd_block. For dasd_device related queue lists the ccwdev lock must be
used.

Fix the mentioned issues by correctly using the ccwdev lock instead of
the queue lock.

Fixes: 583d6535cb ("dasd: remove dead code")
Cc: stable@vger.kernel.org # v5.0+
Signed-off-by: Jan Höppner <hoeppner@linux.ibm.com>
Reviewed-by: Stefan Haberland <sth@linux.ibm.com>
Signed-off-by: Stefan Haberland <sth@linux.ibm.com>
Link: https://lore.kernel.org/r/20230609153750.1258763-2-sth@linux.ibm.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jan Höppner 2023-06-09 17:37:50 +02:00 committed by Greg Kroah-Hartman
parent 6f5c0eec89
commit 1e1e2ee0cf
1 changed files with 2 additions and 2 deletions
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4
drivers/s390/block/dasd_ioctl.c
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@ -552,10 +552,10 @@ static int __dasd_ioctl_information(struct dasd_block *block,
memcpy(dasd_info->type, base->discipline->name, 4);
spin_lock_irqsave(&block->queue_lock, flags);
spin_lock_irqsave(get_ccwdev_lock(base->cdev), flags);
list_for_each(l, &base->ccw_queue)
dasd_info->chanq_len++;
spin_unlock_irqrestore(&block->queue_lock, flags);
spin_unlock_irqrestore(get_ccwdev_lock(base->cdev), flags);
return 0;
}