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Date: Wed, 5 Sep 2012 17:09:15 +0200
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org
Cc: target-devel@...r.kernel.org, nab@...ux-iscsi.org
Subject: [PATCH 3.6 3/3] target: fix use-after-free with PSCSI sense data
The pointer to the sense buffer is fetched by transport_get_sense_data,
but this is called by target_complete_ok_work long after pscsi_req_done
has freed the struct that contains it.
Pass instead the fabric's sense buffer to transport_complete,
and copy the data to it directly in transport_complete. Setting
SCF_TRANSPORT_TASK_SENSE also becomes a duty of transport_complete.
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
drivers/target/target_core_pscsi.c | 21 ++++++------------
drivers/target/target_core_transport.c | 36 ++++++++++++-------------------
include/target/target_core_backend.h | 4 ++-
3 files changed, 24 insertions(+), 37 deletions(-)
diff --git a/drivers/target/target_core_pscsi.c b/drivers/target/target_core_pscsi.c
index 5552fa7..5f7151d 100644
--- a/drivers/target/target_core_pscsi.c
+++ b/drivers/target/target_core_pscsi.c
@@ -667,7 +667,8 @@ static void pscsi_free_device(void *p)
kfree(pdv);
}
-static int pscsi_transport_complete(struct se_cmd *cmd, struct scatterlist *sg)
+static void pscsi_transport_complete(struct se_cmd *cmd, struct scatterlist *sg,
+ unsigned char *sense_buffer)
{
struct pscsi_dev_virt *pdv = cmd->se_dev->dev_ptr;
struct scsi_device *sd = pdv->pdv_sd;
@@ -679,7 +680,7 @@ static int pscsi_transport_complete(struct se_cmd *cmd, struct scatterlist *sg)
* not been allocated because TCM is handling the emulation directly.
*/
if (!pt)
- return 0;
+ return;
cdb = &pt->pscsi_cdb[0];
result = pt->pscsi_result;
@@ -750,10 +751,10 @@ after_mode_sense:
}
after_mode_select:
- if (status_byte(result) & CHECK_CONDITION)
- return 1;
-
- return 0;
+ if (sense_buffer && (status_byte(result) & CHECK_CONDITION)) {
+ memcpy(sense_buffer, pt->pscsi_sense, TRANSPORT_SENSE_BUFFER);
+ cmd->se_cmd_flags |= SCF_TRANSPORT_TASK_SENSE;
+ }
}
enum {
@@ -1184,13 +1185,6 @@ fail:
return -ENOMEM;
}
-static unsigned char *pscsi_get_sense_buffer(struct se_cmd *cmd)
-{
- struct pscsi_plugin_task *pt = cmd->priv;
-
- return pt->pscsi_sense;
-}
-
/* pscsi_get_device_rev():
*
*
@@ -1273,7 +1267,6 @@ static struct se_subsystem_api pscsi_template = {
.check_configfs_dev_params = pscsi_check_configfs_dev_params,
.set_configfs_dev_params = pscsi_set_configfs_dev_params,
.show_configfs_dev_params = pscsi_show_configfs_dev_params,
- .get_sense_buffer = pscsi_get_sense_buffer,
.get_device_rev = pscsi_get_device_rev,
.get_device_type = pscsi_get_device_type,
.get_blocks = pscsi_get_blocks,
diff --git a/drivers/target/target_core_transport.c b/drivers/target/target_core_transport.c
index ea01807..09028af 100644
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -568,38 +568,31 @@ static void target_complete_failure_work(struct work_struct *work)
}
/*
- * Used to obtain Sense Data from underlying Linux/SCSI struct scsi_cmnd
+ * Used when asking transport to copy Sense Data from the underlying
+ * Linux/SCSI struct scsi_cmnd
*/
-static void transport_get_sense_data(struct se_cmd *cmd)
+static unsigned char *transport_get_sense_buffer(struct se_cmd *cmd)
{
- unsigned char *buffer = cmd->sense_buffer, *sense_buffer = NULL;
+ unsigned char *buffer = cmd->sense_buffer;
struct se_device *dev = cmd->se_dev;
- unsigned long flags;
u32 offset = 0;
WARN_ON(!cmd->se_lun);
if (!dev)
- return;
-
- spin_lock_irqsave(&cmd->t_state_lock, flags);
- if (cmd->se_cmd_flags & SCF_SENT_CHECK_CONDITION) {
- spin_unlock_irqrestore(&cmd->t_state_lock, flags);
- return;
- }
+ return NULL;
- sense_buffer = dev->transport->get_sense_buffer(cmd);
- spin_unlock_irqrestore(&cmd->t_state_lock, flags);
+ if (cmd->se_cmd_flags & SCF_SENT_CHECK_CONDITION)
+ return NULL;
offset = cmd->se_tfo->set_fabric_sense_len(cmd, TRANSPORT_SENSE_BUFFER);
- memcpy(&buffer[offset], sense_buffer, TRANSPORT_SENSE_BUFFER);
-
/* Automatically padded */
cmd->scsi_sense_length = TRANSPORT_SENSE_BUFFER + offset;
- pr_debug("HBA_[%u]_PLUG[%s]: Set SAM STATUS: 0x%02x and sense\n",
+ pr_debug("HBA_[%u]_PLUG[%s]: Requesting sense for SAM STATUS: 0x%02x\n",
dev->se_hba->hba_id, dev->transport->name, cmd->scsi_status);
+ return &buffer[offset];
}
void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
@@ -615,11 +608,11 @@ void target_complete_cmd(struct se_cmd *cmd, u8 scsi_status)
cmd->transport_state &= ~CMD_T_BUSY;
if (dev && dev->transport->transport_complete) {
- if (dev->transport->transport_complete(cmd,
- cmd->t_data_sg) != 0) {
- cmd->se_cmd_flags |= SCF_TRANSPORT_TASK_SENSE;
+ dev->transport->transport_complete(cmd,
+ cmd->t_data_sg,
+ transport_get_sense_buffer(cmd));
+ if (cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE)
success = 1;
- }
}
/*
@@ -1982,12 +1975,11 @@ static void target_complete_ok_work(struct work_struct *work)
schedule_work(&cmd->se_dev->qf_work_queue);
/*
- * Check if we need to retrieve a sense buffer from
+ * Check if we need to send a sense buffer from
* the struct se_cmd in question.
*/
if (cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) {
WARN_ON(!cmd->scsi_status);
- transport_get_sense_data(cmd);
ret = transport_send_check_condition_and_sense(
cmd, 0, 1);
if (ret == -EAGAIN || ret == -ENOMEM)
diff --git a/include/target/target_core_backend.h b/include/target/target_core_backend.h
index f1405d3..8d591e4 100644
--- a/include/target/target_core_backend.h
+++ b/include/target/target_core_backend.h
@@ -23,7 +23,9 @@ struct se_subsystem_api {
struct se_device *(*create_virtdevice)(struct se_hba *,
struct se_subsystem_dev *, void *);
void (*free_device)(void *);
- int (*transport_complete)(struct se_cmd *cmd, struct scatterlist *);
+ void (*transport_complete)(struct se_cmd *cmd,
+ struct scatterlist *,
+ unsigned char *);
int (*parse_cdb)(struct se_cmd *cmd);
ssize_t (*check_configfs_dev_params)(struct se_hba *,
--
1.7.1
--
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