From a18a920c70d48a8e4a2b750d8a183b3c1a4be514 Mon Sep 17 00:00:00 2001 From: "Moger, Babu" Date: Wed, 26 Oct 2011 14:29:38 -0400 Subject: [PATCH] [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 Cc: stable@kernel.org Signed-off-by: James Bottomley --- drivers/scsi/device_handler/scsi_dh.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) diff --git a/drivers/scsi/device_handler/scsi_dh.c b/drivers/scsi/device_handler/scsi_dh.c index 7c05fd9dccfd..339ea23a8675 100644 --- a/drivers/scsi/device_handler/scsi_dh.c +++ b/drivers/scsi/device_handler/scsi_dh.c @@ -441,7 +441,15 @@ int scsi_dh_activate(struct request_queue *q, activate_complete fn, void *data) spin_lock_irqsave(q->queue_lock, flags); sdev = q->queuedata; - if (sdev && sdev->scsi_dh_data) + if (!sdev) { + spin_unlock_irqrestore(q->queue_lock, flags); + err = SCSI_DH_NOSYS; + if (fn) + fn(data, err); + return err; + } + + if (sdev->scsi_dh_data) scsi_dh = sdev->scsi_dh_data->scsi_dh; dev = get_device(&sdev->sdev_gendev); if (!scsi_dh || !dev ||