From: Christoph Hellwig hch@lst.de
We should only call dma_max_mapping_size for devices that have a DMA mask set, otherwise we can run into a NULL pointer dereference that will crash the system.
Also we need to do right shift to get the sectors from the size in bytes, not a left shift.
Fixes: bdd17bdef7d8 ("scsi: core: take the DMA max mapping size into account") Reported-by: Bart Van Assche bvanassche@acm.org Reported-by: Ming Lei tom.leiming@gmail.com Tested-by: Guilherme G. Piccoli gpiccoli@canonical.com Signed-off-by: Christoph Hellwig hch@lst.de Signed-off-by: Martin K. Petersen martin.petersen@oracle.com (cherry picked from commit 1b5d9a6e98350e0713b4faa1b04e8f239f63b581) --- drivers/scsi/scsi_lib.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/scsi/scsi_lib.c b/drivers/scsi/scsi_lib.c index 9381171c2fc0..11e64b50497f 100644 --- a/drivers/scsi/scsi_lib.c +++ b/drivers/scsi/scsi_lib.c @@ -1784,8 +1784,10 @@ void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q) blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize); }
- shost->max_sectors = min_t(unsigned int, shost->max_sectors, - dma_max_mapping_size(dev) << SECTOR_SHIFT); + if (dev->dma_mask) { + shost->max_sectors = min_t(unsigned int, shost->max_sectors, + dma_max_mapping_size(dev) >> SECTOR_SHIFT); + } blk_queue_max_hw_sectors(q, shost->max_sectors); if (shost->unchecked_isa_dma) blk_queue_bounce_limit(q, BLK_BOUNCE_ISA);