diff options
| author | Nicholas Bellinger <nab@linux-iscsi.org> | 2017-03-27 16:12:43 -0700 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2017-04-21 09:31:21 +0200 |
| commit | 92f8aa7bb825eafc3686cdda6dbbce44d8b35e75 (patch) | |
| tree | 90df925eeaf5d255e7dc450a85f43b1ee8583c3b /include | |
| parent | 08383b004426591502b86bfacdc638d85cedf26c (diff) | |
target: Avoid mappedlun symlink creation during lun shutdown
commit 49cb77e297dc611a1b795cfeb79452b3002bd331 upstream.
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>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/target/target_core_base.h | 1 |
1 files changed, 1 insertions, 0 deletions
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index 6233e8fd95b5..0383c601e17c 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -705,6 +705,7 @@ struct se_lun { u64 unpacked_lun; #define SE_LUN_LINK_MAGIC 0xffff7771 u32 lun_link_magic; + bool lun_shutdown; bool lun_access_ro; u32 lun_index; |