diff options
| author | Nicholas Bellinger <nab@linux-iscsi.org> | 2017-03-27 16:12:43 -0700 |
|---|---|---|
| committer | Nicholas Bellinger <nab@linux-iscsi.org> | 2017-03-30 01:36:52 -0700 |
| commit | 49cb77e297dc611a1b795cfeb79452b3002bd331 (patch) | |
| tree | 5a4b04abb770f691c69acf8a92277a6271137137 /drivers/target | |
| parent | efb2ea770bb3b0f40007530bc8b0c22f36e1c5eb (diff) | |
| download | linux-49cb77e297dc611a1b795cfeb79452b3002bd331.tar.bz2 | |
target: Avoid mappedlun symlink creation during lun shutdown
This patch closes a race between se_lun deletion during configfs
unlink in target_fabric_port_unlink() -> core_dev_del_lun()
-> core_tpg_remove_lun(), when transport_clear_lun_ref() blocks
waiting for percpu_ref RCU grace period to finish, but a new
NodeACL mappedlun is added before the RCU grace period has
completed.
This can happen in target_fabric_mappedlun_link() because it
only checks for se_lun->lun_se_dev, which is not cleared until
after transport_clear_lun_ref() percpu_ref RCU grace period
finishes.
This bug originally manifested as NULL pointer dereference
OOPsen in target_stat_scsi_att_intr_port_show_attr_dev() on
v4.1.y code, because it dereferences lun->lun_se_dev without
a explicit NULL pointer check.
In post v4.1 code with target-core RCU conversion, the code
in target_stat_scsi_att_intr_port_show_attr_dev() no longer
uses se_lun->lun_se_dev, but the same race still exists.
To address the bug, go ahead and set se_lun>lun_shutdown as
early as possible in core_tpg_remove_lun(), and ensure new
NodeACL mappedlun creation in target_fabric_mappedlun_link()
fails during se_lun shutdown.
Reported-by: James Shen <jcs@datera.io>
Cc: James Shen <jcs@datera.io>
Tested-by: James Shen <jcs@datera.io>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/target')
| -rw-r--r-- | drivers/target/target_core_fabric_configfs.c | 5 | ||||
| -rw-r--r-- | drivers/target/target_core_tpg.c | 4 |
2 files changed, 9 insertions, 0 deletions
diff --git a/drivers/target/target_core_fabric_configfs.c b/drivers/target/target_core_fabric_configfs.c index d8a16ca6baa5..d1e6cab8e3d3 100644 --- a/drivers/target/target_core_fabric_configfs.c +++ b/drivers/target/target_core_fabric_configfs.c @@ -92,6 +92,11 @@ static int target_fabric_mappedlun_link( pr_err("Source se_lun->lun_se_dev does not exist\n"); return -EINVAL; } + if (lun->lun_shutdown) { + pr_err("Unable to create mappedlun symlink because" + " lun->lun_shutdown=true\n"); + return -EINVAL; + } se_tpg = lun->lun_tpg; nacl_ci = &lun_acl_ci->ci_parent->ci_group->cg_item; diff --git a/drivers/target/target_core_tpg.c b/drivers/target/target_core_tpg.c index 6fb191914f45..dfaef4d3b2d2 100644 --- a/drivers/target/target_core_tpg.c +++ b/drivers/target/target_core_tpg.c @@ -642,6 +642,8 @@ void core_tpg_remove_lun( */ struct se_device *dev = rcu_dereference_raw(lun->lun_se_dev); + lun->lun_shutdown = true; + core_clear_lun_from_tpg(lun, tpg); /* * Wait for any active I/O references to percpu se_lun->lun_ref to @@ -663,6 +665,8 @@ void core_tpg_remove_lun( } if (!(dev->se_hba->hba_flags & HBA_FLAGS_INTERNAL_USE)) hlist_del_rcu(&lun->link); + + lun->lun_shutdown = false; mutex_unlock(&tpg->tpg_lun_mutex); percpu_ref_exit(&lun->lun_ref); |