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scsi_mq_setup_tags(), which is called by scsi_add_host(), calculates the command size to allocate based on the prot_capabilities. In the isci driver, scsi_host_set_prot() is called after scsi_add_host() so the command size gets calculated to be smaller than it needs to be. Eventually, scsi_mq_init_request() locates the 'prot_sdb' after the command assuming it was sized correctly and a buffer overrun may occur. However, seeing blk_mq_alloc_rqs() rounds up to the nearest cache line size, the mistake can go unnoticed. The bug was noticed after the struct request size was reduced by commit9d037ad707("block: remove req->timeout_list") Which likely reduced the allocated space for the request by an entire cache line, enough that the overflow could be hit and it caused a panic, on boot, at: RIP: 0010:t10_pi_complete+0x77/0x1c0 Call Trace: <IRQ> sd_done+0xf5/0x340 scsi_finish_command+0xc3/0x120 blk_done_softirq+0x83/0xb0 __do_softirq+0xa1/0x2e6 irq_exit+0xbc/0xd0 call_function_single_interrupt+0xf/0x20 </IRQ> sd_done() would call scsi_prot_sg_count() which reads the number of entities in 'prot_sdb', but seeing 'prot_sdb' is located after the end of the allocated space it reads a garbage number and erroneously calls t10_pi_complete(). To prevent this, the calls to scsi_host_set_prot() are moved into isci_host_alloc() before the call to scsi_add_host(). Out of caution, also move the similar call to scsi_host_set_guard(). Fixes:3d2d752549("[SCSI] isci: T10 DIF support") Link: http://lkml.kernel.org/r/da851333-eadd-163a-8c78-e1f4ec5ec857@deltatee.com Signed-off-by: Logan Gunthorpe <logang@deltatee.com> Cc: Intel SCU Linux support <intel-linux-scu@intel.com> Cc: Artur Paszkiewicz <artur.paszkiewicz@intel.com> Cc: "James E.J. Bottomley" <jejb@linux.ibm.com> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: Christoph Hellwig <hch@lst.de> Cc: Jens Axboe <axboe@kernel.dk> Cc: Jeff Moyer <jmoyer@redhat.com> Reviewed-by: Jeff Moyer <jmoyer@redhat.com> Reviewed-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.