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authorNicholas Bellinger <nab@linux-iscsi.org>2017-10-27 22:19:26 -0800
committerNicholas Bellinger <nab@linux-iscsi.org>2017-11-07 19:50:24 -0800
commit1c21a48055a67ceb693e9c2587824a8de60a217c (patch)
tree43fd75f6f3cfc05510242b7d9a40fa9740b9b18a /drivers/target
parent9574a497df2bbc0a676b609ce0dd24d237cee3a6 (diff)
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target: Avoid early CMD_T_PRE_EXECUTE failures during ABORT_TASK
This patch fixes bug where early se_cmd exceptions that occur before backend execution can result in use-after-free if/when a subsequent ABORT_TASK occurs for the same tag. Since an early se_cmd exception will have had se_cmd added to se_session->sess_cmd_list via target_get_sess_cmd(), it will not have CMD_T_COMPLETE set by the usual target_complete_cmd() backend completion path. This causes a subsequent ABORT_TASK + __target_check_io_state() to signal ABORT_TASK should proceed. As core_tmr_abort_task() executes, it will bring the outstanding se_cmd->cmd_kref count down to zero releasing se_cmd, after se_cmd has already been queued with error status into fabric driver response path code. To address this bug, introduce a CMD_T_PRE_EXECUTE bit that is set at target_get_sess_cmd() time, and cleared immediately before backend driver dispatch in target_execute_cmd() once CMD_T_ACTIVE is set. Then, check CMD_T_PRE_EXECUTE within __target_check_io_state() to determine when an early exception has occured, and avoid aborting this se_cmd since it will have already been queued into fabric driver response path code. Reported-by: Donald White <dew@datera.io> Cc: Donald White <dew@datera.io> Cc: Mike Christie <mchristi@redhat.com> Cc: Hannes Reinecke <hare@suse.com> Cc: stable@vger.kernel.org # 3.14+ Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Diffstat (limited to 'drivers/target')
-rw-r--r--drivers/target/target_core_tmr.c9
-rw-r--r--drivers/target/target_core_transport.c2
2 files changed, 11 insertions, 0 deletions
diff --git a/drivers/target/target_core_tmr.c b/drivers/target/target_core_tmr.c
index 61909b23e959..9c7bc1ca341a 100644
--- a/drivers/target/target_core_tmr.c
+++ b/drivers/target/target_core_tmr.c
@@ -133,6 +133,15 @@ static bool __target_check_io_state(struct se_cmd *se_cmd,
spin_unlock(&se_cmd->t_state_lock);
return false;
}
+ if (se_cmd->transport_state & CMD_T_PRE_EXECUTE) {
+ if (se_cmd->scsi_status) {
+ pr_debug("Attempted to abort io tag: %llu early failure"
+ " status: 0x%02x\n", se_cmd->tag,
+ se_cmd->scsi_status);
+ spin_unlock(&se_cmd->t_state_lock);
+ return false;
+ }
+ }
if (sess->sess_tearing_down || se_cmd->cmd_wait_set) {
pr_debug("Attempted to abort io tag: %llu already shutdown,"
" skipping\n", se_cmd->tag);
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 0e89db84b200..58caacd54a3b 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1975,6 +1975,7 @@ void target_execute_cmd(struct se_cmd *cmd)
}
cmd->t_state = TRANSPORT_PROCESSING;
+ cmd->transport_state &= ~CMD_T_PRE_EXECUTE;
cmd->transport_state |= CMD_T_ACTIVE | CMD_T_SENT;
spin_unlock_irq(&cmd->t_state_lock);
@@ -2667,6 +2668,7 @@ int target_get_sess_cmd(struct se_cmd *se_cmd, bool ack_kref)
ret = -ESHUTDOWN;
goto out;
}
+ se_cmd->transport_state |= CMD_T_PRE_EXECUTE;
list_add_tail(&se_cmd->se_cmd_list, &se_sess->sess_cmd_list);
out:
spin_unlock_irqrestore(&se_sess->sess_cmd_lock, flags);