Re: [PATCH 3/4] scsi: core: Cap shost max_sectors according to DMA optimum mapping limits

From: Dan Carpenter <dan.carpenter@oracle.com>
To: kbuild@lists.01.org, John Garry <john.garry@huawei.com>,
	damien.lemoal@opensource.wdc.com, joro@8bytes.org,
	will@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com,
	hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com
Cc: lkp@intel.com, kbuild-all@lists.01.org,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-ide@vger.kernel.org, iommu@lists.linux-foundation.org,
	linux-scsi@vger.kernel.org, liyihang6@hisilicon.com,
	chenxiang66@hisilicon.com, thunder.leizhen@huawei.com,
	John Garry <john.garry@huawei.com>
Subject: Re: [PATCH 3/4] scsi: core: Cap shost max_sectors according to DMA optimum mapping limits
Date: Mon, 23 May 2022 14:08:05 +0300	[thread overview]
Message-ID: <202205210545.gkS834ds-lkp@intel.com> (raw)
In-Reply-To: <1653035003-70312-4-git-send-email-john.garry@huawei.com>

Hi John,

url:    https://github.com/intel-lab-lkp/linux/commits/John-Garry/DMA-mapping-changes-for-SCSI-core/20220520-163049
base:   https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git next
config: s390-randconfig-m031-20220519 (https://download.01.org/0day-ci/archive/20220521/202205210545.gkS834ds-lkp@intel.com/config)
compiler: s390-linux-gcc (GCC) 11.3.0

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>

smatch warnings:
drivers/scsi/hosts.c:243 scsi_add_host_with_dma() warn: variable dereferenced before check 'dma_dev' (see line 228)

vim +/dma_dev +243 drivers/scsi/hosts.c

d139b9bd0e52dd James Bottomley   2009-11-05  209  int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
d139b9bd0e52dd James Bottomley   2009-11-05  210  			   struct device *dma_dev)
^1da177e4c3f41 Linus Torvalds    2005-04-16  211  {
^1da177e4c3f41 Linus Torvalds    2005-04-16  212  	struct scsi_host_template *sht = shost->hostt;
^1da177e4c3f41 Linus Torvalds    2005-04-16  213  	int error = -EINVAL;
^1da177e4c3f41 Linus Torvalds    2005-04-16  214  
91921e016a2199 Hannes Reinecke   2014-06-25  215  	shost_printk(KERN_INFO, shost, "%s\n",
^1da177e4c3f41 Linus Torvalds    2005-04-16  216  			sht->info ? sht->info(shost) : sht->name);
^1da177e4c3f41 Linus Torvalds    2005-04-16  217  
^1da177e4c3f41 Linus Torvalds    2005-04-16  218  	if (!shost->can_queue) {
91921e016a2199 Hannes Reinecke   2014-06-25  219  		shost_printk(KERN_ERR, shost,
91921e016a2199 Hannes Reinecke   2014-06-25  220  			     "can_queue = 0 no longer supported\n");
542bd1377a9630 James Bottomley   2008-04-21  221  		goto fail;
^1da177e4c3f41 Linus Torvalds    2005-04-16  222  	}
^1da177e4c3f41 Linus Torvalds    2005-04-16  223  
50b6cb3516365c Dexuan Cui        2021-10-07  224  	/* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */
50b6cb3516365c Dexuan Cui        2021-10-07  225  	shost->cmd_per_lun = min_t(int, shost->cmd_per_lun,
ea2f0f77538c50 John Garry        2021-05-19  226  				   shost->can_queue);
ea2f0f77538c50 John Garry        2021-05-19  227  
2ad7ba6ca08593 John Garry        2022-05-20 @228  	if (dma_dev->dma_mask) {
                                                            ^^^^^^^^^^^^^^^^^
The patch adds a new unchecked dereference

2ad7ba6ca08593 John Garry        2022-05-20  229  		shost->max_sectors = min_t(unsigned int, shost->max_sectors,
2ad7ba6ca08593 John Garry        2022-05-20  230  				dma_opt_mapping_size(dma_dev) >> SECTOR_SHIFT);
2ad7ba6ca08593 John Garry        2022-05-20  231  	}
2ad7ba6ca08593 John Garry        2022-05-20  232  
0a6ac4ee7c2109 Christoph Hellwig 2017-01-03  233  	error = scsi_init_sense_cache(shost);
0a6ac4ee7c2109 Christoph Hellwig 2017-01-03  234  	if (error)
0a6ac4ee7c2109 Christoph Hellwig 2017-01-03  235  		goto fail;
0a6ac4ee7c2109 Christoph Hellwig 2017-01-03  236  
d285203cf647d7 Christoph Hellwig 2014-01-17  237  	error = scsi_mq_setup_tags(shost);
542bd1377a9630 James Bottomley   2008-04-21  238  	if (error)
542bd1377a9630 James Bottomley   2008-04-21  239  		goto fail;
d285203cf647d7 Christoph Hellwig 2014-01-17  240  
^1da177e4c3f41 Linus Torvalds    2005-04-16  241  	if (!shost->shost_gendev.parent)
^1da177e4c3f41 Linus Torvalds    2005-04-16  242  		shost->shost_gendev.parent = dev ? dev : &platform_bus;
3c8d9a957d0ae6 James Bottomley   2012-05-04 @243  	if (!dma_dev)
                                                            ^^^^^^^^
The old code checked for NULL

3c8d9a957d0ae6 James Bottomley   2012-05-04  244  		dma_dev = shost->shost_gendev.parent;
3c8d9a957d0ae6 James Bottomley   2012-05-04  245  
d139b9bd0e52dd James Bottomley   2009-11-05  246  	shost->dma_dev = dma_dev;
^1da177e4c3f41 Linus Torvalds    2005-04-16  247  
5c6fab9d558470 Mika Westerberg   2016-02-18  248  	/*
5c6fab9d558470 Mika Westerberg   2016-02-18  249  	 * Increase usage count temporarily here so that calling
5c6fab9d558470 Mika Westerberg   2016-02-18  250  	 * scsi_autopm_put_host() will trigger runtime idle if there is
5c6fab9d558470 Mika Westerberg   2016-02-18  251  	 * nothing else preventing suspending the device.
5c6fab9d558470 Mika Westerberg   2016-02-18  252  	 */
5c6fab9d558470 Mika Westerberg   2016-02-18  253  	pm_runtime_get_noresume(&shost->shost_gendev);
bc4f24014de58f Alan Stern        2010-06-17  254  	pm_runtime_set_active(&shost->shost_gendev);
bc4f24014de58f Alan Stern        2010-06-17  255  	pm_runtime_enable(&shost->shost_gendev);
bc4f24014de58f Alan Stern        2010-06-17  256  	device_enable_async_suspend(&shost->shost_gendev);
bc4f24014de58f Alan Stern        2010-06-17  257  

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