From 76b40319a1ea75682aee6b660fac6dc2e8168c3d Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Jan=20H=C3=B6ppner?= Date: Fri, 9 Jun 2023 17:37:50 +0200 Subject: [PATCH] s390/dasd: Use correct lock while counting channel queue length MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit commit ccc45cb4e7271c74dbb27776ae8f73d84557f5c6 upstream. The lock around counting the channel queue length in the BIODASDINFO ioctl was incorrectly changed to the dasd_block->queue_lock with commit 583d6535cb9d ("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: 583d6535cb9d ("dasd: remove dead code") Cc: stable@vger.kernel.org # v5.0+ Signed-off-by: Jan Höppner Reviewed-by: Stefan Haberland Signed-off-by: Stefan Haberland Link: https://lore.kernel.org/r/20230609153750.1258763-2-sth@linux.ibm.com Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- drivers/s390/block/dasd_ioctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/s390/block/dasd_ioctl.c b/drivers/s390/block/dasd_ioctl.c index cb6427fb9f3d..6d5c9cb83592 100644 --- a/drivers/s390/block/dasd_ioctl.c +++ b/drivers/s390/block/dasd_ioctl.c @@ -505,10 +505,10 @@ 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; }