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target: Fix NULL dereference during LUN lookup + active I/O shutdown

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am: 17ea11d553

Change-Id: I2c9b9e4596cdb9bb666de90603c41d4dfc26aaea
This commit is contained in:
Nicholas Bellinger
2017-03-15 02:23:28 +00:00
committed by android-build-merger
parent 9ac636111c 17ea11d553
commit c45b44d5d8
4 changed files with 41 additions and 4 deletions
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10
drivers/target/target_core_device.c
View File

@@ -77,12 +77,16 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
&deve->read_bytes);
se_lun = rcu_dereference(deve->se_lun);
if (!percpu_ref_tryget_live(&se_lun->lun_ref)) {
se_lun = NULL;
goto out_unlock;
}
se_cmd->se_lun = rcu_dereference(deve->se_lun);
se_cmd->pr_res_key = deve->pr_res_key;
se_cmd->orig_fe_lun = unpacked_lun;
se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
percpu_ref_get(&se_lun->lun_ref);
se_cmd->lun_ref_active = true;
if ((se_cmd->data_direction == DMA_TO_DEVICE) &&
@@ -96,6 +100,7 @@ transport_lookup_cmd_lun(struct se_cmd *se_cmd, u64 unpacked_lun)
goto ref_dev;
}
}
out_unlock:
rcu_read_unlock();
if (!se_lun) {
@@ -815,6 +820,7 @@ struct se_device *target_alloc_device(struct se_hba *hba, const char *name)
xcopy_lun = &dev->xcopy_lun;
rcu_assign_pointer(xcopy_lun->lun_se_dev, dev);
init_completion(&xcopy_lun->lun_ref_comp);
init_completion(&xcopy_lun->lun_shutdown_comp);
INIT_LIST_HEAD(&xcopy_lun->lun_deve_list);
INIT_LIST_HEAD(&xcopy_lun->lun_dev_link);
mutex_init(&xcopy_lun->lun_tg_pt_md_mutex);

3
drivers/target/target_core_tpg.c
View File

@@ -445,7 +445,7 @@ static void core_tpg_lun_ref_release(struct percpu_ref *ref)
{
struct se_lun *lun = container_of(ref, struct se_lun, lun_ref);
complete(&lun->lun_ref_comp);
complete(&lun->lun_shutdown_comp);
}
int core_tpg_register(
@@ -571,6 +571,7 @@ struct se_lun *core_tpg_alloc_lun(
lun->lun_link_magic = SE_LUN_LINK_MAGIC;
atomic_set(&lun->lun_acl_count, 0);
init_completion(&lun->lun_ref_comp);
init_completion(&lun->lun_shutdown_comp);
INIT_LIST_HEAD(&lun->lun_deve_list);
INIT_LIST_HEAD(&lun->lun_dev_link);
atomic_set(&lun->lun_tg_pt_secondary_offline, 0);

31
drivers/target/target_core_transport.c
View File

@@ -2702,10 +2702,39 @@ void target_wait_for_sess_cmds(struct se_session *se_sess)
}
EXPORT_SYMBOL(target_wait_for_sess_cmds);
static void target_lun_confirm(struct percpu_ref *ref)
{
struct se_lun *lun = container_of(ref, struct se_lun, lun_ref);
complete(&lun->lun_ref_comp);
}
void transport_clear_lun_ref(struct se_lun *lun)
{
percpu_ref_kill(&lun->lun_ref);
/*
* Mark the percpu-ref as DEAD, switch to atomic_t mode, drop
* the initial reference and schedule confirm kill to be
* executed after one full RCU grace period has completed.
*/
percpu_ref_kill_and_confirm(&lun->lun_ref, target_lun_confirm);
/*
* The first completion waits for percpu_ref_switch_to_atomic_rcu()
* to call target_lun_confirm after lun->lun_ref has been marked
* as __PERCPU_REF_DEAD on all CPUs, and switches to atomic_t
* mode so that percpu_ref_tryget_live() lookup of lun->lun_ref
* fails for all new incoming I/O.
*/
wait_for_completion(&lun->lun_ref_comp);
/*
* The second completion waits for percpu_ref_put_many() to
* invoke ->release() after lun->lun_ref has switched to
* atomic_t mode, and lun->lun_ref.count has reached zero.
*
* At this point all target-core lun->lun_ref references have
* been dropped via transport_lun_remove_cmd(), and it's safe
* to proceed with the remaining LUN shutdown.
*/
wait_for_completion(&lun->lun_shutdown_comp);
}
static bool

1
include/target/target_core_base.h
View File

@@ -732,6 +732,7 @@ struct se_lun {
struct config_group lun_group;
struct se_port_stat_grps port_stat_grps;
struct completion lun_ref_comp;
struct completion lun_shutdown_comp;
struct percpu_ref lun_ref;
struct list_head lun_dev_link;
struct hlist_node link;