3.16.66-rc1 review patch. If anyone has any objections, please let me know.
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From: Logan Gunthorpe logang@deltatee.com
commit cc29a1b0a3f2597ce887d339222fa85b9307706d upstream.
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 commit 9d037ad707ed ("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: 3d2d75254915 ("[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 Signed-off-by: Ben Hutchings ben@decadent.org.uk --- drivers/scsi/isci/init.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-)
--- a/drivers/scsi/isci/init.c +++ b/drivers/scsi/isci/init.c @@ -598,6 +598,13 @@ static struct isci_host *isci_host_alloc shost->max_lun = ~0; shost->max_cmd_len = MAX_COMMAND_SIZE;
+ /* turn on DIF support */ + scsi_host_set_prot(shost, + SHOST_DIF_TYPE1_PROTECTION | + SHOST_DIF_TYPE2_PROTECTION | + SHOST_DIF_TYPE3_PROTECTION); + scsi_host_set_guard(shost, SHOST_DIX_GUARD_CRC); + err = scsi_add_host(shost, &pdev->dev); if (err) goto err_shost; @@ -685,13 +692,6 @@ static int isci_pci_probe(struct pci_dev goto err_host_alloc; } pci_info->hosts[i] = h; - - /* turn on DIF support */ - scsi_host_set_prot(to_shost(h), - SHOST_DIF_TYPE1_PROTECTION | - SHOST_DIF_TYPE2_PROTECTION | - SHOST_DIF_TYPE3_PROTECTION); - scsi_host_set_guard(to_shost(h), SHOST_DIX_GUARD_CRC); }
err = isci_setup_interrupts(pdev);