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scsi: core: fix the dma_max_mapping_size call 

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: bdd17bdef7 ("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>
This commit is contained in:
Christoph Hellwig 2019-07-22 11:20:38 +02:00 committed by Martin K. Petersen
parent e70bdd81bf
commit 1b5d9a6e98
1 changed files with 4 additions and 2 deletions
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6
drivers/scsi/scsi_lib.c
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@ -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);