Commit f9b0530f authored Jul 12, 2019 by Ming Lei Committed by Martin K. Petersen Jul 16, 2019

scsi: core: Fix race on creating sense cache



When scsi_init_sense_cache(host) is called concurrently from different
hosts, each code path may find that no cache has been created and
allocate a new one. The lack of locking can lead to potentially
overriding a cache allocated by a different host.

Fix the issue by moving 'mutex_lock(&scsi_sense_cache_mutex)' before
scsi_select_sense_cache().

Fixes: 0a6ac4ee ("scsi: respect unchecked_isa_dma for blk-mq")
Cc: Stable <stable@vger.kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Hannes Reinecke <hare@suse.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

parent 0cdc5858

drivers/scsi/scsi_lib.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -84,11 +84,11 @@ int scsi_init_sense_cache(struct Scsi_Host *shost)
		struct kmem_cache *cache;
		int ret = 0;

		mutex_lock(&scsi_sense_cache_mutex);
		cache = scsi_select_sense_cache(shost->unchecked_isa_dma);
		if (cache)
		return 0;
		goto exit;

		mutex_lock(&scsi_sense_cache_mutex);
		if (shost->unchecked_isa_dma) {
		scsi_sense_isadma_cache =
		kmem_cache_create("scsi_sense_cache(DMA)",
		@@ -104,7 +104,7 @@ int scsi_init_sense_cache(struct Scsi_Host *shost)
		if (!scsi_sense_cache)
		ret = -ENOMEM;
		}

		exit:
		mutex_unlock(&scsi_sense_cache_mutex);
		return ret;
		}

Admin message