| From | Greg Kroah-Hartman <> | Subject | [PATCH 4.14 115/293] scsi: core: Fix race on creating sense cache | Date | Mon, 29 Jul 2019 21:20:06 +0200 |
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From: Ming Lei <ming.lei@redhat.com>
commit f9b0530fa02e0c73f31a49ef743e8f44eb8e32cc upstream.
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: 0a6ac4ee7c21 ("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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/scsi/scsi_lib.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -71,11 +71,11 @@ int scsi_init_sense_cache(struct Scsi_Ho 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)", @@ -90,7 +90,7 @@ int scsi_init_sense_cache(struct Scsi_Ho if (!scsi_sense_cache) ret = -ENOMEM; } - + exit: mutex_unlock(&scsi_sense_cache_mutex); return ret; }
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