* [PATCH 1/2] iscsi-target: Fix rx_login_comp hang after login failure
2015-11-15 0:21 [PATCH 0/2] target: kthread login failure hung task + CAW use-after-free Nicholas A. Bellinger
@ 2015-11-15 0:21 ` Nicholas A. Bellinger
2015-11-16 11:27 ` Sagi Grimberg
2015-11-15 0:21 ` [PATCH 2/2] target: Fix race for SCF_COMPARE_AND_WRITE_POST checking Nicholas A. Bellinger
2015-12-18 13:05 ` [PATCH 0/2] target: kthread login failure hung task + CAW use-after-free Martin Svec
2 siblings, 1 reply; 6+ messages in thread
From: Nicholas A. Bellinger @ 2015-11-15 0:21 UTC (permalink / raw)
To: target-devel; +Cc: linux-scsi, Nicholas Bellinger, Sagi Grimberg
From: Nicholas Bellinger <nab@linux-iscsi.org>
This patch addresses a case where iscsi_target_do_tx_login_io()
fails sending the last login response PDU, after the RX/TX
threads have already been started.
The case centers around iscsi_target_rx_thread() not invoking
allow_signal(SIGINT) before the send_sig(SIGINT, ...) occurs
from the failure path, resulting in RX thread hanging
indefinately on iscsi_conn->rx_login_comp.
Note this bug is a regression introduced by:
commit e54198657b65625085834847ab6271087323ffea
Author: Nicholas Bellinger <nab@linux-iscsi.org>
Date: Wed Jul 22 23:14:19 2015 -0700
iscsi-target: Fix iscsit_start_kthreads failure OOPs
To address this bug, complete ->rx_login_complete for good
measure in the failure path, and immediately return from
RX thread context if connection state did not actually reach
full feature phase (TARG_CONN_STATE_LOGGED_IN).
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: <stable@vger.kernel.org> # v3.10+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
drivers/target/iscsi/iscsi_target.c | 13 ++++++++++++-
drivers/target/iscsi/iscsi_target_nego.c | 1 +
2 files changed, 13 insertions(+), 1 deletion(-)
diff --git a/drivers/target/iscsi/iscsi_target.c b/drivers/target/iscsi/iscsi_target.c
index 342a07c..72204fb 100644
--- a/drivers/target/iscsi/iscsi_target.c
+++ b/drivers/target/iscsi/iscsi_target.c
@@ -4074,6 +4074,17 @@ reject:
return iscsit_add_reject(conn, ISCSI_REASON_BOOKMARK_NO_RESOURCES, buf);
}
+static bool iscsi_target_check_conn_state(struct iscsi_conn *conn)
+{
+ bool ret;
+
+ spin_lock_bh(&conn->state_lock);
+ ret = (conn->conn_state != TARG_CONN_STATE_LOGGED_IN);
+ spin_unlock_bh(&conn->state_lock);
+
+ return ret;
+}
+
int iscsi_target_rx_thread(void *arg)
{
int ret, rc;
@@ -4091,7 +4102,7 @@ int iscsi_target_rx_thread(void *arg)
* incoming iscsi/tcp socket I/O, and/or failing the connection.
*/
rc = wait_for_completion_interruptible(&conn->rx_login_comp);
- if (rc < 0)
+ if (rc < 0 || iscsi_target_check_conn_state(conn))
return 0;
if (conn->conn_transport->transport_type == ISCSI_INFINIBAND) {
diff --git a/drivers/target/iscsi/iscsi_target_nego.c b/drivers/target/iscsi/iscsi_target_nego.c
index 5c964c0..9fc9117 100644
--- a/drivers/target/iscsi/iscsi_target_nego.c
+++ b/drivers/target/iscsi/iscsi_target_nego.c
@@ -388,6 +388,7 @@ err:
if (login->login_complete) {
if (conn->rx_thread && conn->rx_thread_active) {
send_sig(SIGINT, conn->rx_thread, 1);
+ complete(&conn->rx_login_comp);
kthread_stop(conn->rx_thread);
}
if (conn->tx_thread && conn->tx_thread_active) {
--
1.9.1
^ permalink raw reply related [flat|nested] 6+ messages in thread* [PATCH 2/2] target: Fix race for SCF_COMPARE_AND_WRITE_POST checking
2015-11-15 0:21 [PATCH 0/2] target: kthread login failure hung task + CAW use-after-free Nicholas A. Bellinger
2015-11-15 0:21 ` [PATCH 1/2] iscsi-target: Fix rx_login_comp hang after login failure Nicholas A. Bellinger
@ 2015-11-15 0:21 ` Nicholas A. Bellinger
2015-12-18 13:05 ` [PATCH 0/2] target: kthread login failure hung task + CAW use-after-free Martin Svec
2 siblings, 0 replies; 6+ messages in thread
From: Nicholas A. Bellinger @ 2015-11-15 0:21 UTC (permalink / raw)
To: target-devel; +Cc: linux-scsi, Nicholas Bellinger, Sagi Grimberg
From: Nicholas Bellinger <nab@linux-iscsi.org>
This patch addresses a race + use after free where the first
stage of COMPARE_AND_WRITE in compare_and_write_callback()
is rescheduled after the backend sends the secondary WRITE,
resulting in second stage compare_and_write_post() callback
completing in target_complete_ok_work() before the first
can return.
Because current code depends on checking se_cmd->se_cmd_flags
after return from se_cmd->transport_complete_callback(),
this results in first stage having SCF_COMPARE_AND_WRITE_POST
set, which incorrectly falls through into second stage CAW
processing code, eventually triggering a NULL pointer
dereference due to use after free.
To address this bug, pass in a new *post_ret parameter into
se_cmd->transport_complete_callback(), and depend upon this
value instead of ->se_cmd_flags to determine when to return
or fall through into ->queue_status() code for CAW.
Cc: Sagi Grimberg <sagig@mellanox.com>
Cc: <stable@vger.kernel.org> # v3.12+
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
---
drivers/target/target_core_sbc.c | 13 +++++++++----
drivers/target/target_core_transport.c | 14 ++++++++------
include/target/target_core_base.h | 2 +-
3 files changed, 18 insertions(+), 11 deletions(-)
diff --git a/drivers/target/target_core_sbc.c b/drivers/target/target_core_sbc.c
index 0b4b2a6..ae24d0f 100644
--- a/drivers/target/target_core_sbc.c
+++ b/drivers/target/target_core_sbc.c
@@ -371,7 +371,8 @@ sbc_setup_write_same(struct se_cmd *cmd, unsigned char *flags, struct sbc_ops *o
return 0;
}
-static sense_reason_t xdreadwrite_callback(struct se_cmd *cmd, bool success)
+static sense_reason_t xdreadwrite_callback(struct se_cmd *cmd, bool success,
+ int *post_ret)
{
unsigned char *buf, *addr;
struct scatterlist *sg;
@@ -437,7 +438,8 @@ sbc_execute_rw(struct se_cmd *cmd)
cmd->data_direction);
}
-static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success)
+static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success,
+ int *post_ret)
{
struct se_device *dev = cmd->se_dev;
@@ -447,8 +449,10 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success)
* sent to the backend driver.
*/
spin_lock_irq(&cmd->t_state_lock);
- if ((cmd->transport_state & CMD_T_SENT) && !cmd->scsi_status)
+ if ((cmd->transport_state & CMD_T_SENT) && !cmd->scsi_status) {
cmd->se_cmd_flags |= SCF_COMPARE_AND_WRITE_POST;
+ *post_ret = 1;
+ }
spin_unlock_irq(&cmd->t_state_lock);
/*
@@ -460,7 +464,8 @@ static sense_reason_t compare_and_write_post(struct se_cmd *cmd, bool success)
return TCM_NO_SENSE;
}
-static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool success)
+static sense_reason_t compare_and_write_callback(struct se_cmd *cmd, bool success,
+ int *post_ret)
{
struct se_device *dev = cmd->se_dev;
struct scatterlist *write_sg = NULL, *sg;
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index 5bacc7b..010b8c4 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -1658,7 +1658,7 @@ bool target_stop_cmd(struct se_cmd *cmd, unsigned long *flags)
void transport_generic_request_failure(struct se_cmd *cmd,
sense_reason_t sense_reason)
{
- int ret = 0;
+ int ret = 0, post_ret = 0;
pr_debug("-----[ Storage Engine Exception for cmd: %p ITT: 0x%08llx"
" CDB: 0x%02x\n", cmd, cmd->tag, cmd->t_task_cdb[0]);
@@ -1680,7 +1680,7 @@ void transport_generic_request_failure(struct se_cmd *cmd,
*/
if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) &&
cmd->transport_complete_callback)
- cmd->transport_complete_callback(cmd, false);
+ cmd->transport_complete_callback(cmd, false, &post_ret);
switch (sense_reason) {
case TCM_NON_EXISTENT_LUN:
@@ -2068,11 +2068,13 @@ static void target_complete_ok_work(struct work_struct *work)
*/
if (cmd->transport_complete_callback) {
sense_reason_t rc;
+ bool caw = (cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE);
+ bool zero_dl = !(cmd->data_length);
+ int post_ret = 0;
- rc = cmd->transport_complete_callback(cmd, true);
- if (!rc && !(cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE_POST)) {
- if ((cmd->se_cmd_flags & SCF_COMPARE_AND_WRITE) &&
- !cmd->data_length)
+ rc = cmd->transport_complete_callback(cmd, true, &post_ret);
+ if (!rc && !post_ret) {
+ if (caw && zero_dl)
goto queue_rsp;
return;
diff --git a/include/target/target_core_base.h b/include/target/target_core_base.h
index 8b9c727..61a0393 100644
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -474,7 +474,7 @@ struct se_cmd {
struct completion cmd_wait_comp;
const struct target_core_fabric_ops *se_tfo;
sense_reason_t (*execute_cmd)(struct se_cmd *);
- sense_reason_t (*transport_complete_callback)(struct se_cmd *, bool);
+ sense_reason_t (*transport_complete_callback)(struct se_cmd *, bool, int *);
void *protocol_data;
unsigned char *t_task_cdb;
--
1.9.1
^ permalink raw reply related [flat|nested] 6+ messages in thread