Date: Tue, 26 Feb 2008 23:30:02 +0100 (CET) From: Stefan Richter Subject: firewire: fw-sbp2: better fix for NULL pointer dereference in scsi_remove_device Patch "firewire: fw-sbp2: fix NULL pointer deref. in scsi_remove_device" had the unintended effect that firewire-sbp2 could not be unloaded anymore until all SBP-2 devices were unplugged. We now fix the NULL pointer bug by reacquiring a reference to the sdev instead of holding a reference to the sdev (and to the module) all the time. Signed-off-by: Stefan Richter Tested-by: Jarod Wilson --- drivers/firewire/fw-sbp2.c | 46 +++++++++++++++++++++---------------- 1 file changed, 27 insertions(+), 19 deletions(-) Index: linux/drivers/firewire/fw-sbp2.c =================================================================== --- linux.orig/drivers/firewire/fw-sbp2.c +++ linux/drivers/firewire/fw-sbp2.c @@ -122,7 +122,6 @@ static const char sbp2_driver_name[] = " struct sbp2_logical_unit { struct sbp2_target *tgt; struct list_head link; - struct scsi_device *sdev; struct fw_address_handler address_handler; struct list_head orb_list; @@ -139,6 +138,7 @@ struct sbp2_logical_unit { int generation; int retries; struct delayed_work work; + bool has_sdev; bool blocked; }; @@ -751,20 +751,33 @@ static void sbp2_unblock(struct sbp2_tar scsi_unblock_requests(shost); } +static int sbp2_lun2int(u16 lun) +{ + struct scsi_lun eight_bytes_lun; + + memset(&eight_bytes_lun, 0, sizeof(eight_bytes_lun)); + eight_bytes_lun.scsi_lun[0] = (lun >> 8) & 0xff; + eight_bytes_lun.scsi_lun[1] = lun & 0xff; + + return scsilun_to_int(&eight_bytes_lun); +} + static void sbp2_release_target(struct kref *kref) { struct sbp2_target *tgt = container_of(kref, struct sbp2_target, kref); struct sbp2_logical_unit *lu, *next; struct Scsi_Host *shost = container_of((void *)tgt, struct Scsi_Host, hostdata[0]); + struct scsi_device *sdev; /* prevent deadlocks */ sbp2_unblock(tgt); list_for_each_entry_safe(lu, next, &tgt->lu_list, link) { - if (lu->sdev) { - scsi_remove_device(lu->sdev); - scsi_device_put(lu->sdev); + sdev = scsi_device_lookup(shost, 0, 0, sbp2_lun2int(lu->lun)); + if (sdev) { + scsi_remove_device(sdev); + scsi_device_put(sdev); } sbp2_send_management_orb(lu, tgt->node_id, lu->generation, SBP2_LOGOUT_REQUEST, lu->login_id, NULL); @@ -807,7 +820,6 @@ static void sbp2_login(struct work_struc struct fw_device *device = fw_device(tgt->unit->device.parent); struct Scsi_Host *shost; struct scsi_device *sdev; - struct scsi_lun eight_bytes_lun; struct sbp2_login_response response; int generation, node_id, local_node_id; @@ -820,7 +832,7 @@ static void sbp2_login(struct work_struc local_node_id = device->card->node_id; /* If this is a re-login attempt, log out, or we might be rejected. */ - if (lu->sdev) + if (lu->has_sdev) sbp2_send_management_orb(lu, device->node_id, generation, SBP2_LOGOUT_REQUEST, lu->login_id, NULL); @@ -859,7 +871,7 @@ static void sbp2_login(struct work_struc sbp2_agent_reset(lu); /* This was a re-login. */ - if (lu->sdev) { + if (lu->has_sdev) { sbp2_cancel_orbs(lu); sbp2_conditionally_unblock(lu); goto out; @@ -868,13 +880,8 @@ static void sbp2_login(struct work_struc if (lu->tgt->workarounds & SBP2_WORKAROUND_DELAY_INQUIRY) ssleep(SBP2_INQUIRY_DELAY); - memset(&eight_bytes_lun, 0, sizeof(eight_bytes_lun)); - eight_bytes_lun.scsi_lun[0] = (lu->lun >> 8) & 0xff; - eight_bytes_lun.scsi_lun[1] = lu->lun & 0xff; shost = container_of((void *)tgt, struct Scsi_Host, hostdata[0]); - - sdev = __scsi_add_device(shost, 0, 0, - scsilun_to_int(&eight_bytes_lun), lu); + sdev = __scsi_add_device(shost, 0, 0, sbp2_lun2int(lu->lun), lu); /* * FIXME: We are unable to perform reconnects while in sbp2_login(). * Therefore __scsi_add_device() will get into trouble if a bus reset @@ -896,7 +903,8 @@ static void sbp2_login(struct work_struc } /* No error during __scsi_add_device() */ - lu->sdev = sdev; + lu->has_sdev = true; + scsi_device_put(sdev); sbp2_allow_block(lu); goto out; @@ -934,11 +942,11 @@ static int sbp2_add_logical_unit(struct return -ENOMEM; } - lu->tgt = tgt; - lu->sdev = NULL; - lu->lun = lun_entry & 0xffff; - lu->retries = 0; - lu->blocked = false; + lu->tgt = tgt; + lu->lun = lun_entry & 0xffff; + lu->retries = 0; + lu->has_sdev = false; + lu->blocked = false; ++tgt->dont_block; INIT_LIST_HEAD(&lu->orb_list); INIT_DELAYED_WORK(&lu->work, sbp2_login);