[SCSI] scsi_dh: check queuedata pointer before proceeding further
This patch validates sdev pointer in scsi_dh_activate before proceeding further. Without this check we might see the panic as below. I have seen this panic multiple times.. Call trace: #0 [ffff88007d647b50] machine_kexec at ffffffff81020902 #1 [ffff88007d647ba0] crash_kexec at ffffffff810875b0 #2 [ffff88007d647c70] oops_end at ffffffff8139c650 #3 [ffff88007d647c90] __bad_area_nosemaphore at ffffffff8102dd15 #4 [ffff88007d647d50] page_fault at ffffffff8139b8cf [exception RIP: scsi_dh_activate+0x82] RIP: ffffffffa0041922 RSP: ffff88007d647e00 RFLAGS: 00010046 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 00000000000093c5 RDX: 00000000000093c5 RSI: ffffffffa02e6640 RDI: ffff88007cc88988 RBP: 000000000000000f R8: ffff88007d646000 R9: 0000000000000000 R10: ffff880082293790 R11: 00000000ffffffff R12: ffff88007cc88988 R13: 0000000000000000 R14: 0000000000000286 R15: ffff880037b845e0 ORIG_RAX: ffffffffffffffff CS: 0010 SS: 0000 #5 [ffff88007d647e38] run_workqueue at ffffffff81060268 #6 [ffff88007d647e78] worker_thread at ffffffff81060386 #7 [ffff88007d647ee8] kthread at ffffffff81064436 #8 [ffff88007d647f48] kernel_thread at ffffffff81003fba Signed-off-by: Babu Moger <babu.moger@netapp.com> Cc: stable@kernel.org Signed-off-by: James Bottomley <JBottomley@Parallels.com>
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@ -441,7 +441,15 @@ int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *data)
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spin_lock_irqsave(q->queue_lock, flags);
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spin_lock_irqsave(q->queue_lock, flags);
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sdev = q->queuedata;
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sdev = q->queuedata;
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if (sdev && sdev->scsi_dh_data)
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if (!sdev) {
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spin_unlock_irqrestore(q->queue_lock, flags);
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err = SCSI_DH_NOSYS;
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if (fn)
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fn(data, err);
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return err;
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}
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if (sdev->scsi_dh_data)
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scsi_dh = sdev->scsi_dh_data->scsi_dh;
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scsi_dh = sdev->scsi_dh_data->scsi_dh;
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dev = get_device(&sdev->sdev_gendev);
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dev = get_device(&sdev->sdev_gendev);
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if (!scsi_dh || !dev ||
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if (!scsi_dh || !dev ||
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