dm: fix potential for q->make_request_fn NULL pointer (47ace7e0) · Commits · 戴 / test

Move blk_queue_make_request() to dm.c:alloc_dev() so that q->make_request_fn is never NULL during the lifetime of a DM device (even one that is created without a DM table). Otherwise generic_make_request() will crash simply by doing: dmsetup create -n test mount /dev/dm-N /mnt While at it, move ->congested_data initialization out of dm.c:alloc_dev() and into the bio-based specific init method. Reported-by:

Stefan Bader <stefan.bader@canonical.com> BugLink: https://bugs.launchpad.net/bugs/1860231 Fixes: ("dm: remove request-based logic from make_request_fn wrapper") Depends-on: ("dm: various cleanups to md->queue initialization code") Cc: stable@vger.kernel.org Signed-off-by:

Mike Snitzer <snitzer@redhat.com>

drivers/md/dm.c

+7 −2

Original line number	Diff line number	Diff line
		@@ -1859,6 +1859,7 @@ static void dm_init_normal_md_queue(struct mapped_device *md)
		/*
		* Initialize aspects of queue that aren't relevant for blk-mq
		*/
		md->queue->backing_dev_info->congested_data = md;
		md->queue->backing_dev_info->congested_fn = dm_any_congested;
		}

		@@ -1949,7 +1950,12 @@ static struct mapped_device *alloc_dev(int minor)
		if (!md->queue)
		goto bad;
		md->queue->queuedata = md;
		md->queue->backing_dev_info->congested_data = md;
		/*
		* default to bio-based required ->make_request_fn until DM
		* table is loaded and md->type established. If request-based
		* table is loaded: blk-mq will override accordingly.
		*/
		blk_queue_make_request(md->queue, dm_make_request);

		md->disk = alloc_disk_node(1, md->numa_node_id);
		if (!md->disk)
		@@ -2264,7 +2270,6 @@ int dm_setup_md_queue(struct mapped_device md, struct dm_table t)
		case DM_TYPE_DAX_BIO_BASED:
		case DM_TYPE_NVME_BIO_BASED:
		dm_init_normal_md_queue(md);
		blk_queue_make_request(md->queue, dm_make_request);
		break;
		case DM_TYPE_NONE:
		WARN_ON_ONCE(true);

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