The patch below does not apply to the 4.9-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@xxxxxxxxxxxxxxx>.
thanks,
greg k-h
------------------ original commit in Linus's tree ------------------
>From 1c21a48055a67ceb693e9c2587824a8de60a217c Mon Sep 17 00:00:00 2001
From: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
Date: Fri, 27 Oct 2017 22:19:26 -0800
Subject: [PATCH] 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@xxxxxxxxx>
Cc: Donald White <dew@xxxxxxxxx>
Cc: Mike Christie <mchristi@xxxxxxxxxx>
Cc: Hannes Reinecke <hare@xxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 3.14+
Signed-off-by: Nicholas Bellinger <nab@xxxxxxxxxxxxxxx>
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);
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index d3139a95ea77..ccf501b8359c 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -490,6 +490,7 @@ struct se_cmd {
#define CMD_T_STOP (1 << 5)
#define CMD_T_TAS (1 << 10)
#define CMD_T_FABRIC_STOP (1 << 11)
+#define CMD_T_PRE_EXECUTE (1 << 12)
spinlock_t t_state_lock;
struct kref cmd_kref;
struct completion t_transport_stop_comp;