diff options
| author | Nicholas Bellinger <nab@linux-iscsi.org> | 2017-03-27 16:12:43 -0700 |
|---|---|---|
| committer | Moyster <oysterized@gmail.com> | 2017-11-06 15:26:33 +0100 |
| commit | 59b8327019ccf798cc6334637e005c5ea1a6f792 (patch) | |
| tree | 034181009bdca05331dcd44228a4abf7c7bd1225 | |
| parent | f07aaebdae10eddbbd4b12c2fa3de7b1965c576a (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>
Cc: stable@vger.kernel.org # 3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Willy Tarreau <w@1wt.eu>
| -rw-r--r-- | drivers/target/target_core_fabric_configfs.c | 5 | ||||
| -rw-r--r-- | drivers/target/target_core_tpg.c | 3 | ||||
| -rw-r--r-- | include/target/target_core_base.h | 1 |
3 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 04c775cb3..179f7810d 100644 --- a/drivers/target/target_core_fabric_configfs.c +++ b/drivers/target/target_core_fabric_configfs.c @@ -84,6 +84,11 @@ static int target_fabric_mappedlun_link( "_tpg 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_sep->sep_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 8572207e3..bc3092f03 100644 --- a/drivers/target/target_core_tpg.c +++ b/drivers/target/target_core_tpg.c @@ -839,6 +839,8 @@ static void core_tpg_shutdown_lun( struct se_portal_group *tpg, struct se_lun *lun) { + lun->lun_shutdown = true; + core_clear_lun_from_tpg(lun, tpg); transport_clear_lun_from_sessions(lun); } @@ -868,6 +870,7 @@ struct se_lun *core_tpg_pre_dellun( spin_unlock(&tpg->tpg_lun_lock); return ERR_PTR(-ENODEV); } + lun->lun_shutdown = false; spin_unlock(&tpg->tpg_lun_lock); return lun; diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h index 7d99c0b5b..8e271438f 100644 --- a/include/target/target_core_base.h +++ b/include/target/target_core_base.h @@ -729,6 +729,7 @@ struct se_port_stat_grps { struct se_lun { #define SE_LUN_LINK_MAGIC 0xffff7771 u32 lun_link_magic; + bool lun_shutdown; /* See transport_lun_status_table */ enum transport_lun_status_table lun_status; u32 lun_access; |